— ^  mmikKY  PRINCIPLES 


OF 


IIFIC  AGRICULTURE 


<.  T.  LUPTOM 


■BMMMttana 


/B  .-^ 


# 


UNIVERSITY  of  CALIFORNJ/ 
LOS  ANCiri.KS 


THE 


ELEMENTARY    PRINCIPLES 


OF 


SClEiNTIFIC  AGRICULTURE..:;, 


^^         ■> 


PROFESSOR    OF    CHEMISTRV  Jt^  VANDM^^LT    UNUVKSLrir,>flASIMW-S 


NEW  YORK  •:•  CINCINNATI  •:•  CHICAGO 
AMERICAN     BOOK     COMPANY. 

S\T5C 


PRIMER  SERIES. 

SCIENCE  PRIMERS. 

HUXLEY  S  INTRODUCTORY  VOLUME. 

ROSCOES  CHEMISTRY. 

STEWART'S  PHYSICS. 

GEIKIE'S  GEOLOGY. 

LOCKYER'S   ASTRONOMY. 

HOOKER'S   BOTANY. 

FOSTER  AND  TRACY'S  PHYSIOLOGY  AND 

HYGIENE. 
GEIKIE'S  PHYSICAL  GEOGRAPHY. 
LUPrON'S  SCIENTIFIC  AGRICULTURE. 
JEVONSS  LOGIC. 

SPENCER  S  INVENTIONAL  GEOMETRY. 
lEVONS'S  POLITICAL  ECONOMY. 
TAYLOR  S  PIANOFORTE  PLAYING. 
PATTON'S  NATURAL  RESOURCES  OF  THE 

UNITED  STATES. 

HISTORY   PRIMERS. 

WENDELS  HISTORY  OF  EGYPT. 
FREEMAN'S  HISTORY  OF  EUROPE. 
FYFFE'S  HISTORY  OF  GREECE. 
CREIGHTON'S  HISTORY  OF  ROME. 
MAHAFFY'S  OLD  GREEK  LIFE. 
WILKIN'SS   ROMAN  ANTIQUITIES. 
TIGHE'S  ROMAN  CONSTITUTION. 
ADA.MS  S  MEDIAEVAL  CIVILIZATION. 
YONGE'S  HISTORY  OF  FRANCE. 
GROVE'S  GEOGRAPHY. 

LITERATURE  PRIMERS. 

BROOKES  ENGLISH  LITERATURE. 
WATKINS'S  AMERICAN  LITERATURE. 
DOVVDEN  S  SHAKSPERE. 
ALDEN  S  STUDIES  IN  BRYANT. 
MORRIS  S   ENGLISH  GRAMMAR. 
MORRIS  AND   BOWEN'S  ENGLISH 

GRAMMAR   EXERCISES 
NICHOLS   FNGLISH  COMPOSITION. 
PEILE'S  PHILOLOGY. 
J  EBB'S    GREEK  LITER.\TURE. 
GLADSTONES  HOMER. 
TOZER  S  CLASSICAL  GEOGRAPHV. 


LUPTON— SCI.  ACK. 

Copyright,  1880,  by  D  .APPLETON  &  CO. 
W.   P.  5 


PREFACE. 


The  following  communication  explains  the  rea- 
son that  induced  the  author  to  present  to  the  public 
this  little  work  on  "  The  Elementary  Principles  of 
Scientific  Agriculture  " : 

Nashville,  Tenn.,  December  17,  1879. 
In  accordance  with  Chapter  CLXXXVI.,  Acts 
of  the  General  Assembly  of  Tennessee,  approved 
March  27, 1879,  which  directs  "that  the  Superinten- 
dent of  Public  Instruction  and  the  Commissioner 
of  Agriculture  shall  be  constituted  a  commission  to 
procure  the  preparation  of,  or  the  designation  of  a 
work  on  the  Elementary  Principles  of  Agriculture 
which  shall  be  taught  in  the  public  schools  of  the 
State,  as  are  the  other  studies  prescribed  in  the  21st 
section  of  the  Public  School  Law,"  the  undersigned 
have  "procured  the  preparation  "  of  a  work  as  here- 
in described,  by  Professor  N.  T.  Lupton,  Professor 
of  Chemistry,  Vanderbilt  University;  and,  having 
carefully   examined   the    MS.,  hereby   approve   the 


4  PREFACE. 

same    and   adopt  it,   to    be   taught   in   the  public 
schools  of  the  State,  in  accordance  with  the  express 
terms  of  said  act. 
(Signed)      , 
Commis-  \  Leon  Trousdai-e,  State  Superintendent, 


1 


noners.  [  J.  B.  KiLLEBREW,  Com.  of  Agriculture. 

In  response  to  this  demand  for  the  introduction 
of  the  "  Elementary  Principles  of  Agriculture  "  into 
the  regular  course  of  study  in  the  public  schools, 
the  author  has  endeavored  to  present  the  subject 
in  clear,  concise  language,  avoiding  technical  terms, 
except  where  scientific  accuracy  required  their  use. 
As  the  principles  discussed  are  of  universal  applica- 
tion, this  little  work  is  designed  for  general  use,  being 
adapted  to  every  section  where  agriculture  is  taught 
and  practiced  as  a  science.  It  is  believed  that  intel- 
ligent farmers  and  planters  will  find  it  sufficiently  plain 
and  practical  for  profitable  reading  and  study. 

The  attention  of  teachers  is  called  to  a  few  sim- 
ple experiments  in  the  Appendix,  to  which  reference 
is  made  in  the  text  by  corresponding  figures  inclosed 
in  parentheses.  The  performance  of  even  a  few  ex- 
periments will  add  greatly  to  the  interest  of  pupils 
in  the  facts  and  principles  presented. 


CONTENTS. 


CHAPTER  SECTIONS  PAGE 

I.  The  Development  of  Scientific  Ag- 
riculture      i-ii  7 

/flj  The  Origin,  Composition,  and  Clas- 

^^        SIFICATION   OF  SOILS          i           ,          »  12-49  12 

III.  The  Composition  of  Plants       .        .  50-70  27 

IV.  Composition  and  Properties  of  the 

Atmosphere 71-82  35 

V.  The  Sources  of  Plant-Food,  and  how 

obtained 83-95  39 

VI.  The  Improvement  of  Soils    .        .  96-110  45 
VII.  The  Use  of  Manures  or  Fertilizers  111-157  51 
VIII.  Mineral  Fertilizers    ....  158-176  70 
IX.  Rotation  of  Crops  ....  177-188  79 
X.  The   Selection   and   Care  of  Live- 
stock     189-200  84 

Appendix 90 

Questions 95 


Digitized  by  tine  Internet  Arcliive 

in  2007  with  funding  from 

IVIicrosoft  Corporation 


littp://www.arcliive.org/details/elementaryprinciOOIuptiala 


ELEMENTARY   PRINCIPLES 


SCIENTIFIC  AGRICULTURE. 


2.  /  1  S6> 

CHAPTER  I. 


THE   DEVELOPMENT    OF    SCIENTIFIC    AGRICULTURE. 

1.  Agriculture  is  both  a  science  and  an  art. 
As  an  art,  it  teaches  how  to  cultivate  the  soil,  make 
and  use  fertilizers,  take  care  of  stock,  and  do  what- 
ever is  necessary  for  the  successful  management  of 
a  farm.  As  a  science,  it  explains  the  growth  of 
plants  and  animals,  and  the  principles  upon  which 
the  practical  operations  of  farming  depend.  As  an 
art,  it  tells  what  to  do  ;  as  a  science,  it  explains  tha 
reasons  for  what  is  done. 

2.  Agriculture,  like  other  sciences,  was  practised 
as  an  art  long  before  the  principles  upon  which  it  is 
based  were  understood.  As  an  industrial  pursuit,  it . 
has  always  been  the  first  in  importance.  This  is 
owing  to  the  fact  that  man's  necessities  compel  him  to 
cultivate  the  soil.     While  the  earth  of  its  own  accord 


8  SCIENTIFIC  AGRICULTURE. 

produces  enough  food  for  the  support  of  the  lower 
animals,  man  is  forced  to  earn  his  bread  by  the  sweat 
of  his  brow. 

3.  In  the  early  ages  of  the  world,  the  population 
was  small,  and  the  wants  of  men  so  few  that  very  lit- 
tle cultivation  of  the  soil  was  required.  The  rivers 
and  forests  supplied,  in  a  great  measure,  both  food 
and  clothing,  until  the  increase  of  population  origi- 
nated necessities  and  luxuries  which  could  only  be 
satisfied  by  increased  cultivation. 

4.  Although  agriculture,  as  an  art,  has  been  prac- 
tised to  some  extent  by  all  nations,  and  in  every  age 
of  the  world,  its  progress  as  a  science  has  been  very 
slow.  In  fact,  sciences  of  recent  origin  have  made 
much  greater  progress  and  are  at  this  day  more  gen- 
erally understood.  There  are  men  even  now  who 
say  that  practical  and  scientific  farming  are  very 
different ;  in  other  words,  that  agriculture  is  no  sci- 
ence at  all.  This  is  because  they  do  not  understand 
its  principles,  or  have  a  false  notion  of  what  scientific 
agriculture  really  is. 

5.  There  are  several  reasons  for  the  slow  prog- 
ress or  growth  of  agriculture  as  a  science.  In  the 
first  place,  the  dignity  and  importance  of  the  pursuit 
were  not  fully  recognized  until  within  recent  times. 
It  is  true  that,  in  every  age  of  the  world,  some  good 
and  great  men  have  been  farmers.  We  read  in  his- 
tory of  Cincinnatus  leaving  his  plow  at  the  call  of  his 
country,  and  of  Putnam  deserting  his  field  of  agri- 
cultural labor  for  one  of  military  glory,  and  even  of 


DEVELOPMENT.  p 

Washington  retiring  to  Mount  Vernon  to  spend  the 
closing  years  of  a  noble  life  in  the  quiet  occupation 
of  a  farmer.  We  read,  too,  of  Plato,  and  Pliny,  and 
Columella,  and  even  of  Cicero,  living  at  times  on 
their  farms  and  writing  on  subjects  connected  with 
farming  operations.  These  noted  men,  however,  did 
not  practise  farming  as  a  profession,  as  a  perma- 
nent business,  but  rather  as  a  relaxation  from  the 
cares  of  political  life.  To  accomplish  great  results 
in  any  department  of  science  requires  that  we  make 
it  more  than  a  recreation,  more  than  a  pastime. 
It  must  be  the  study  of  a  lifetime. 

6.  Again,  agriculture  has  made  slow  progress  as 
a  science,  because  it  is  closely  connected  with  and 
dependent  on  other  sciences  which  are  themselves  of 
recent  origin.  A  good  farmer  must  know  something  of 
Botany,  the  science  of  plants,  whether  he  finds  it  out 
by  observation  or  learns  it  from  books,  that  he  may 
understand  the  character  of  the  various  products  of 
the  soil,  and  be  enabled  to  adapt  his  mode  of  culti- 
vation to  the  nature  of  his  crop. 

7.  The  farmer  must  know,  at  least  practically, 
something  of  Zoology,  the  science  of  animals,  that  he 
may  procure  and  raise  such  stock  as  will  be  of  most 
service  to  himself,  and  command  good  prices  in  the 
market.  He  must  be  something  of  a  geologist,  that 
is,  must  know  enough  of  Geology,  the  science  that 
treats  of  the  structure  and  formation  of  the  earth, 
its  soil  and  rocks,  to  enable  him  to  understand  the 
nature  of  soils,  and  be  able  to  judge  of  their  value  by 


lO  SCIENTIFIC  AGRICULTURE. 

mere  inspection.  If  not  a  mechanic  himself,  the  me- 
chanic arts  must  be  understood  by  those  who  furnish 
him  with  plows  and  wagons  and  other  farming  im- 
plements. The  science  of  Physics,  which  treats  of 
the  general  properties  of  bodies,  and  the  causes — 
such  as  light,  heat,  and  electricity — that  modify  these 
properties,  is  also  important ;  and,  finally,  the  farmer 
ought  to  have  some  knowledge  of  Chemistry,  in  order 
to  understand  the  constitution  of  soils,  and  plants, 
and  fertilizers,  and  to  enable  him  to  adapt  them 
to  each  other,  and,  when  necessary,  to  determine 
what  ought  to  be  added  to  a  soil  to  make  it  produce 
a  good  crop. 

8.  We  do  not  mean  to  say  that  the  farmer  or 
planter  must  be  skilled  in  all  these  sciences,  but  he 
should  have  at  least  a  general  acquaintance  with 
them  if  he  would  practise  farming  to  the  best  advan- 
tage. To  the  farmer,  they  are  all  profitable  subjects 
for  study,  because  they  are  closely  connected  with 
his  profession,  and  are,  in  fact,  the  foundation  upon 
which  the  science  of  agriculture  is  based. 

9.  Perhaps  the  most  important  practical  results 
to  agriculture  have  been  derived  from  the  science  of 
Mechanics  and  that  of  Chemistry.  The  progress  in 
the  mechanic  arts  is  seen  when  we  compare  the 
farming  implements  now  in  use  with  those  of  for- 
mer times.  The  rough,  uncouth  wooden  plow  has 
given  place  to  various  forms  of  neat,  easy-running 
plows  partly  or  wholly  of  iron,  and  even  these  have 
given  place  in  some  countries  to  the  gang  and  steam 


DEVELOPMENT.  1 1 

plow,  which  do  the  work  of  a  dozen  old-fashioned 
implements.  The  sickle  has  given  place  to  the  cra- 
dle, the  cradle  to  the  reaper,  the  scythe  to  the  mower, 
the  old  tedious  process  of  separating  cotton-seed 
from  the  fiber  by  hand,  to  the  cotton-gin,  and  a  great 
many  other  mechanical  improvements  which  the  in- 
ventive genius  of  the  nineteenth  century  has  given 
to  the  world. 

10.  Among  the  benefits  derived  from  chemistry 
may  be  mentioned : 

1.  It  teaches  the  composition  and  qualities  of 
soils,  of  plants,  of  the  atmosphere,  of  fertilizers. 

2.  It  determines  the  kind  and  quality  of  food 
that  different  plants  need  for  strong,  healthy  growth. 

3.  It  shows  how  to  manufacture  fertilizers,  and  to 
make  use  of  all  sorts  of  refuse  matter  in  the  prepara- 
tion of  food  for  plants. 

4.  It  explains  the  action  of  light,  heat,  and  other 
agencies  in  promoting  growth,  and,  in  a  word,  un- 
folds all  the  conditions  of  fertility. 

11.  The  chemist  in  his  investigations  proceeds 
to  analyze  the  soil,  and  plant,  and  air,  and  fertilizers, 
that  he  may  understand  their  nature  and  the  rela- 
tions they  sustain  to  each  other ;  and  we  propose  to 
inquire  into  the  results  of  these  investigations,  and 
show  in  few  words  what  modern  science  teaches  of 
the  composition  and  use  of  these  substances  with 
which  the  farmer  and  planter  have  so  much  to  do. 


12  SCIENTIFIC  AGRICULTURE. 


CHAPTER  II. 

THE   ORIGIN,   COMPOSITION,    AND    CLASSIFICATION   OF 
SOILS. 

12.  The  earthy  matter  in  which  plants  grow  is 
called  the  soil.  It  consists  of  finely  divided  parti- 
cles of  rock  mixed  with  organic  matter.  The  organic 
matter  comes  chiefly  from  the  decay  of  plants,  and 
forms  generally  a  very  small  portion  of  the  soil.  It 
can  be  easily  burned  off,  leaving  the  mineral  portion, 
which  consists  of  disintegrated  or  finely  crumbled 
rock  (i).  The  earth  is  supposed  by  geologists  to  har^ 
once  been  a  mass  of  melted  matter.  As  it  cooled 
down,  a  crust  was  formed  upon  which  condensed 
moisture  falling  as  rain  wore  away  the  solid  rock, 
being  aided  in  its  corroding  action  by  heat  and  other 
agencies,  until  the  pulverized  or  finely  divided  sur- 
face was  in  proper  condition  to  produce  the  plant. 

Soils  consist  of  a  small  amount  of  organic 
matter  mixed  with  rock  which  has  been  re- 
duced to  a  fine  state  of  division  by  mechanical 
and  chemical  agencies. 

13.  Mechanical  agencies  are  such  as  merely 
alter  the  form  or  appearance  of  bodies  without 
changing  their  character,  Hke  the  grinding  or  rub- 
bing of  rocks  together,  whereby  they  are  broken  into 
small  pieces.  Each  little  piece  has  the  same  prop- 
erties as  the  large  mass.    Chemical  agencies  are 


SOILS. 


M 


such  as  alter  the  real  nature  of  bodies,  as  in  the 
rusting  of  iron  and  the  burning  of  wood.  The  rust 
has  different  properties  from  the  metallic  iron,  and 
the  gases  and  ash  formed  in  burning  are  very  differ- 
ent from  the  original  wood.  In  such  cases,  chemical 
action  has  brought  about  the  change.  Both  these 
agencies  are  all  the  time  at  work  upon  the  rocks,  and, 
though  they  are  generally  slow  in  their  action,  vast 
results  are  finally  produced. 

14.  The  geologist  includes  under  the  term  rock 
all  soils  and  loose  material,  clays,  and  gravel,  as  well 
as  the  large  solid  masses  which  compose  the  earth. 
The  disintegrating,  or  crumbling  action  by  which 
soils  are  formed  is  always  going  on,  plants  and  ani- 
mals doing  a  great  deal  toward  bringing  about  the 
changes  that  are  produced.  The  most  powerful 
agencies  in  the  crumbling  of  rocks  are  air  and  wa- 
ter. Water  not  only  wears  away  rocks  and  reduces 
them  to  powder  by  mechanical  action,  but  it  dis- 
solves them  all  in  a  greater  or  less  degree.  This 
solvent  action  is  greatly  increased  by  the  air  which 
it  contains.  Water  also  soaks  into  soft  rocks  and 
runs  into  holes  and  crevices,  where  freezing  it  ex- 
pands, and  forces  masses  and  particles  of  rock  asun- 
der. One  great  advantage  of  deep,  thorough  culti- 
vation is  that  air  and  moisture  may  penetrate  the 
soil,  and  continue  their  disintegrating  or  crumbling 
action  upon  the  particles  of  rock  of  which  the  soil 
is  composed,  thus  setting  free  the  plant-food  and  pre- 
paring it  as  proper  nourishment  for  the  hungry  plant. 


14 


SCIENTIFIC  AGRICULTURE. 


15.  The  elements  of  a  soil  vary  with  the  kind  of 
solid  rock  from  which  it  was  originally  formed.  A 
disintegrated  sandstone,  or  limestone,  or  slate,  or 
granite,  will  each  produce  a  soil  of  peculiar  charac- 
ter. Very  often  the  soil  rests  upon  the  rock  from 
which  it  was  formed.  Sometimes,  however,  it  has 
been  carried  away  and  deposited  at  a  long  distance 
from  the  parent  rock.  Such  deposits  form  what  are 
called  alluvial  soils,  and  are  generally  found  in  creek 
and  river  bottoms  (2). 

16.  The  great  difference  in  the  quality  and  value 
of  soils  results  mainly  from  a  difference  in  the  rela- 
tive quantity  of  certain  elements  present.  The  total 
absence  of  any  of  the  essential  elements  of  plants  is 
rare.  Notwithstanding  the  great  variety  of  mineral 
and  vegetable  substances,  the  whole  mass  of  the 
earth  and  everything  upon  it  is  composed  of  few 
elements,  or  simple  substances  (3). 

17.  The  number  of  elements  certainly  known  is 
sixty-five;  several  others  have  been  announced 
recently,  but  their  existence  is  yet  in  doubt.  Five 
of  these,  oxygen,  hydrogen,  nitrogen,  chlorine,  and 
fluorine,  are  gases,  and  two,  bromine  and  mercury, 
are  liquids  at  the  ordinary  temperature  of  the  air, 
while  all  the  others  are  solid.  By  reducing  the 
temperature  and  applying  great  pressure,  the  gases 
can  be  changed  to  liquids,  and  the  liquids  can  be 
converted  into  solids.  There  are  no  permanent 
gases  ;  even  oxygen,  hydrogen,  and  nitrogen  have 
been  made  to  assume  the  liquid  form. 


SOILS. 


IS 


i8.  The  farmer  and  planter  are  concerned  with 
only  fourteen  or  fifteen  of  these  elements,  because 
only  this  number  enter  into  the  composition  of  soils 
generally,  and  are  concerned  in  the  growth  of  plants 
These  are  as  follows : 

Noiumetalhc  Elements.  Metallic  Elements. 

1.  Oxygen.  i.  Potassium. 

2.  Hydrogen.  2.  Sodium. 

3.  Nitrogen.  3.  Calcium. 

4.  Carbon.  4.  Magnesium. 

5.  Silicon.  5.  Aluminium. 

6.  Sulphur.  6.  Iron. 

7.  Phosphorus. 

8.  Chlorine. 

To  these  may  be  added  manganese,  iodine,  and 
fluorine,  which  are  sometimes  present  in  minute 
quantities. 

19.  Oxygen  is  by  far  the  most  abundant  of  the 
elements.  It  forms  about  one  half  of  the  solid  crust 
of  the  earth,  eight-ninths  of  all  the  water,  and  one- 
fifth  of  the  atmosphere.  This  element  is  easily  pre- 
pared by  heating  in  a  glass  tube  or  flask  either  mer- 
curic oxide  (commonly  called  red  oxide  of  mercury), 
or  potassium  chlorate.  Heat  separates  the  oxygen 
from  these  compounds.  It  can  easily  be  collected 
in  suitable  vessels  and  its  properties  examined.  If  a 
small  quantity  of  manganese  dioxide  (black  oxide  of 
manganese)  be  mixed  with  the  potassium  chlorate,  the 
oxygen  will  be  given  off  at  a  lower  temperature.   (4). 


l6  SCIENTIFIC  AGRICULTURE. 

20.  Oxygen  is  an  invisible  gas  without  taste  ci 
smell.  It  is  called  a  supporter  of  combustion  because 
wood,  coal,  oil,  gas,  and  other  substances  burn  in  it. 
If  the  oxygen  be  pure  they  burn  with  great  brilliancy. 
Combustion,  such  as  takes  place  in  our  fireplaces, 
stoves,  and  lamps,  is  the  result  of  chemical  union  be- 
tween the  oxygen  of  the  air  and  the  carbon  and  hy- 
drogen of  the  fuel.  The  bright  sparks  that  fly  from 
the  blacksmith's  anvil  are  particles  of  iron  uniting 
with  oxygen. 

21.  Oxygen  unites  to  form  compounds  with  all! 
the  known  elements  except  fluorine.  These  com-- 
pounds  are  called  oxides.  The  compounds  of  oxy- 
gen with  some  of  the  metals  were  originally  named 
by  merely  changing  the  termination  um  or  ium  of 
the  metal  into  a.  These  names  are  still  in  common 
use.     Thus : 

Potassium  hydroxide  is  often  called  potassa  or  potash. 
Sodium  hydroxide  "  "      soda. 

Magnesium  oxide  "  "      magnesia. 

Aluminium  oxide  "  "      alumina. 

Calcium  with  oxygen  forms  lime ;  silicon  forms 
silica  or  pure  white  sand.     According  to  the  new. 
system   of  naming   oxides,  the  name  of  the  metal 
comes  first  with  the  word  oxide  immediately  after. 

22.  Oxygen  sometimes  unites  slowly  and  gradu- 
ally with  other  elements  without  producing  light  or 
intense  heat,  as  when  wood  decays  or  iron  rusts. 
These  are  c^ses  of  oxidation,  and  the  final  results 


SOILS. 


17 


are  the  same  whether  the  action  takes  place  slowly  or 
rapidly.  This  process  of  slow  oxidation  is  constantly 
going  on  in  the  bodies  of  animals.  When  they  breathe, 
the  air  enters  the  lungs,  where  the  oxygen  it  contains 
is  taken  up  or  absorbed  by  the  blood,  and  carried 
throughout  the  body.  Animals  cannot  live  without 
oxygen.     It  is  also  necessary  to  the  growth  of  plants. 

23.  Hydrogen  is  another  abundant  element.  It 
forms  one  ninth  by  weight  of  water  and  enters  into 
the  composition  of  all  plants  and  animals.  It  can 
be  prepared  easily  by  the  action  of  dilute  sulphuric 
or  hydrochloric  acid  on  zinc  or  iron.  If  some  scraps 
of  either  of  these  metals  be  placed  in  a  wineglass 
and  a  little  acid  poured  over  them,  effervescence  will 
be  produced  by  the  escape  of  the  hydrogen  (5). 

24.  Hydrogen  is  the  lightest  substance  known. 
Like  oxygen  it  is  an  invisible  gas  without  color,  taste, 
or  smell,  but  unlike  oxygen  it  will  burn  when  brought 
in  contact  with  flame.  The  flame  of  burning  hydro- 
gen is  of  a  pale-blue  color  and  intensely  hot  (6). 
The  result  of  the  combustion  is  water  (7).  Sixteen 
pounds  of  oxygen  unite  with  two  pounds  of  hydro- 
gen to  form  eighteen  pounds  of  water. 

25.  Water,  which  is  formed  by  the  chemical 
union  of  the  two  elements  just  mentioned,  is  one  of 
the  most  abundant  and  important  compounds  in 
nature.  It  is  easily  converted  into  vapor,  v/hich,  ris- 
ing from  the  surface  of  the  earth  in  an  invisible  form, 
is  afterward  condensed  into  rain,  and  dew,  and 
frost.     It  dissolves  solid,  liquid,  and  gaseous  sub- 


l8  SCIENTIFIC  AGRICULTURE. 

Stances,  and  in  this  way  carries  food  to  the  roots  of 
plants  (8).  All  natural  waters,  such  as  are  found  in 
springs,  wells,  rivers,  and  lakes,  contain  in  solution 
more  or  less  mineral  matter  derived  from  the  soil. 
Rain-water  is  the  purest,  as  it  contains  nothing  in 
solution  except  what  it  gets  from  the  air  as  it  falls 
through  it. 

26.  Nitrogen  is  found  in  the  atmosphere  in 
large  quantity,  and  also  in  plants  and  animals.  It 
forms  four-fifths  of  the  volume  of  the  air.  The  most 
convenient  way  to  prepare  nitrogen  is  to  remove  the 
oxygen  from  air  by  means  of  phosphorus  (9).  Other 
substances  can  also  be  used  for  the  removal  of  the 
oxygen. 

27.  Nitrogen  is  a  colorless  gas  with  no  taste  or 
smell.  It  heither  burns  nor  dges  it  support  combus- 
tion. Animals  cannot  live  in  it,  and  yet  it  is  not 
poisonous.  It  has  no  power  to  sustain  life,  merely 
serving  in  the  atmosphere  to  dilute  the  oxygen.  The 
three  gases  just  mentioned  are  easily  distinguished 
by  means  of  a  lighted  taper.  Oxygen  will  not  burn, 
but  will  make  the  taper  burn  with  great  brilliancy ; 
hydrogen  will  put  out  the  taper,  but  will  burn  itself 
with  a  pale-blue  flame;  nitrogen  will  neither  burn 
nor  will  it  support  the  flame,  but  put  it  out  at  once. 

28.  Ammonia  is  a  very  important  compound  of 
nitrogen  and  hydrogen.  It  is  formed  when  am- 
monium chloride  (sometimes  called  sal-ammoniac) 
is  rubbed  with  common  lime,  and  is  a  gas  of  strong, 
pungent  odor  (10).     It  unites  with  acids,  destroying 


SOILS. 


19 


their  sour  taste.  Water  absorbs  about  seven  hundred 
times  its  volume  of  this  gas,  and  in  this  condition 
it  is  commonly  called  hartshoriL  Ammonia  is 
an  alkali — that  is,  it  neutralizes  acids  and  restores 
vegetable  colors,  like  litmus,  that  have  been  made  red 
by  means  of  an  acid. 

29.  Ammonia  is  formed  naturally  by  the  decay 
of  animal  and  vegetable  matter,  as  in  manure-piles. 
Its  odor  can  be  detected  in  stables,  or  where  organic 
substances  containing  nitrogen  are  undergoing  de- 
composition. As  a  gas  it  exists  in  minute  quantities 
in  the  atmosphere,  .and  finds  its  way  into  plants 
through  their  roots. 

30.  Nitrogen  and  oxygen  unite  to  form  several 
oxides,  one  of  which  when  combined  with  water  is 
known  as  nitric  acid.  This  is  a  very  strong  acid  of 
intensely  sour  taste.  It  corrodes  or  destroys  the 
flesh,  and  acts  upon  nearly  all  the  metals,  forming 
with  them  a  class  of  compounds,  called  nitrates. 
One  of  these,  potassium  nitrate,  is  known  as  nitre  or 
saltpetre;  and  another,  sodium  nitrate,  goes  by  the 
name  of  Chili  saltpetre.  Both  of  these  nitrates  are 
used  as  fertilizers  (ii). 

51.  Carbon  is  an  element  that  exists  in  three 
distinct  forms.  Charcoal,  coke,  and  lampblack  are 
varieties  of  the  first;  graphite,  or  plumbago,  com- 
monly known  as  black  lead  and  used  for  mak- 
ing lead-pencils,  is  the  second;  and  the  diamond, 
which  is  pure  crystallized  carbon,  the  third  and  most 
valuable  form.    When  wood  is  heated  in  a  close  ves- 


20  SCIENTIFIC  AGRICULTURE. 

sel  or  burned  in  a  covered  heap,  the  black  residue  is 
chiefly  carbon.  This  element  forms  the  greater  por- 
tion of  woody  substances  and  enters  largely  into  the 
composition  of  all  organic  matter.  Sugar  contains 
42  per  cent,  of  carbon,  spirits  of  turpentine  88  per 
cent.  The  black  smoke  of  a  candle  or  lamp  is  car- 
bon in  a  finely  divided  state  (12). 

32.  Carbon  dioxide,  or  carbonic  acid  gas, 
is  a  compound  of  carbon  and  oxygen  that  exists  in 
small  quantities  in  the  air,  and  is  always  formed 
when  carbon  burns.  It  is  a  heavy,  poisonous  gas 
that  is  formed  during  respiration,  combustion,  fer- 
mentation, and  decay.  While  it  poisons  animals,  it 
is  an  important  food  for  plants,  as  will  be  shown 
hereafter.  If  a  little  hydrochloric  acid  be  poured 
on  a  piece  of  marble  or  limestone,  the  effervescence 
produced  is  caused  by  the  escape  of  this  gas  (13), 
It  will  extinguish  a  burning  taper. 

33.  Silicon  is  an  element  found  in  common  sand 
and  quartz.  It  is  very  abundant,  forming  about  one- 
fourth  of  the  solid  part  of  the  earth,  but  very  diffi- 
cult to  separate  from  the  oxygen  with  which  it  is  near- 
ly always  combined.  Some  chemists  doubt  whether 
it  is  a  necessary  constituent  of  plants.  It  is  certainly 
found  in  the  stems  of  grass,  wheat,  corn,  and  in  vari- 
ous kinds  of  vegetation, 

34.  Sulphur  is  a  well-known  substance  of  yellow 
color  that  burns  with  a  pale-blue  flame  and  suffocat- 
ing odor.  In  burning,  it  unites  with  the  oxygen  of 
the  air  to  form  sulphur  dioxide,  which  is  used  to  de- 


SOILS.  21 

stroy  bad  odors  and  also  for  bleaching  straw  bonnets, 
hats,  and  other  goods  (14).  Sulphur  in  combination 
with  oxygen  and  hydrogen  forms  sulphuric  acid,  or 
"oil  of  vitriol,"  one  of  the  strongest  of  the  acids. 
This  acid  forms  compounds  known  as  sulphates,  as 
calcium  sulphate,  or  gypsum,  and  magnesium  sulphate, 
or  Epsom  salts  (15). 

35.  Phosphorus  is  a  soft,  slightly  yellow  solid, 
that  gives  off  a  white  smoke  when  exposed  to  the 
air  and  takes  fire  very  easily.  This  white  smoke  is 
caused  by  the  slow  burning  of  the  phosphorus  {16). 
This  element  forms  a  large  percentage  of  the  bones 
of  animals,  and  is  found  in  soils  and  in  plants,  espe- 
cially in  the  seeds.  Phosphorus  takes  fire  so  easily  in 
the  air  that  it  must  be  kept  under  water.  It  is  used 
for  making  matches.  When  the  end  of  a  match  is 
rubbed  against  a  rough  surface,  enough  heat  is  pro- 
duced to  set  fire  to  the  phosphorus ;  this  inflames  the 
sulphur  on  the  match,  and  the  sulphur  sets  fire  to  the 
wood  of  which  the  match  is  made  (17). 

36.  Phosphoric  acid  is  a  compound  of  phos- 
phorus with  oxygen  and  hydrogen  (18).  When  cal- 
cium takes  the  place  of  hydrogen  in  this  acid  it  forms 
calcium  phosphate,  or  bone  phosphate,  the  chief  con- 
stituent of  bones.  This  acid  forms  a  large  class  of 
salts  called  phosphates.  As  animals  get  their  food 
from  plants  and  plants  their  food  from  the  air  and 
soil,  it  is  necessary  for  soils  to  contain  phosphorus. 
When  a  deficiency  of  this  element  does  exist  in  a 
soil,  it  is  usual  to  supply  it  by  means  of  bones. 


22  SCIENTIFIC  AGRICULTURE. 

37.  Chlorine  is  a  heavy  gas  of  a  yellowish-green 
color,  found  only  in  combination  with  other  elements. 
In  combination  with  hydrogen  it  forms  hydrochloric 
acid,  formerly  called  muriatic  acid.  If  this  acid  be 
heated  with  manganese  dioxide,  the  chlorine  will  be 
separated.  It  is  poisonous  when  breathed.  It  will 
destroy  organic  coloring  matters  and  bad-smelling 
gases,  and  hence  is  used  for  bleaching,  and  as  a  dis- 
infectant or  purifier  of  air  (19).  Common  salt  is  a 
compound  of  sodium  and  chlorine.  This  element 
is  found  in  the  ash  of  plants  and  also  in  soils. 

38.  Iodine,  a  dark-colored  solid  that  forms  a 
beautiful  violet  vapor  when  heated,  and  bromine, 
a  dark-red  liquid,  are  found  in  combination  with 
other  elements  in  some  plants.  In  chemical  proper- 
ties they  are  similar  to  chlorine  (20).  Fluorine  is 
the  most  difficult  to  prepare  of  all  the  elements. 
It  is  described  as  a  gas,  and  exists  in  small  quan- 
tities in  the  teeth  of  animals,  and  in  other  por- 
tions of  the  body,  and  also  in  some  plants  and 
minerals. 

39.  Potassium  is  a  soft  metal,  lighter  than  water. 
It  unites  with  oxygen  so  readily  that  it  has  to  be  kept 
under  the  surface  of  naphtha,  a  liquid  that  has  no 
oxygen  in  it.  If  thrown  on  the  surface  of  water,  or 
placed  on  a  piece  of  ice,  it  takes  fire  and  burns  with 
a  beautiful  violet-colored  flame  (21).  In  combina- 
tion with  hydrogen  and  oxygen,  it  forms  caustic  pot- 
ash. All  the  acids  contain  hydrogen.  The  salts  of 
potassium  are  formed  by  replacing  the  hydrogen  of 


SOILS. 


23 


an  acid  with  this  metal.    Some  of  these  salts  are  found 
in  soils  and  in  the  ashes  of  plants. 

40.  Sodium  is  a  soft  metal  very  much  like  po- 
tassium in  appearance  and  in  properties.  It  also 
must  be  kept  under  naphtha,  but  will  not  take  fire 
on  water,  unless  it  be  held  in  one  place,  or  the  water 
be  warmed.  It  spins  around  over  the  water,  decom- 
posing it,  and  forming  caustic  soda  (22).  It  forms  a 
large  number  of  salts.  Common  salt  is  sodium  chlo- 
ride, and  is  found  in  all  salt  springs,  in  the  ocean,  and 
in  soils,  and  the  ashes  of  plants.  Caustic  soda  and. 
caustic  potassa,  or  potash,  are  called  alkalies.  They 
destroy  the  flesh,  neutralize  acids,  and  color  red  lit- 
mus-paper blue  (23).  In  these  respects  they  are 
similar  to  ammonia.  They  are  used  to  make  soap  : 
caustic  potash  to  make  soft  soap,  and  caustic  soda  to 
make  hard  soap. 

41.  Calcium  is  a  metal  very  hard  to  separate 
from  its  compounds.  With  oxygen  it  forms  com- 
mon, unslaked  lime.  Marble,  and  limestone,  and 
chalk,  are  calcium  carbonates,  which  on  being  heat- 
ed lose  carbon  dioxide,  and  are  changed  into  lime. 
Gypsum,  or  land  plaster,  is  calcium  sulphate,  a  valu- 
able fertilizer.  Spring  and  well  water  very  often 
contain  these  salts  in  solution. 

42.  Magnesium  and  aluminium  are  hard,  white 
metals,  the  former  a  constituent  of  dolomite,  or  mag- 
nesian  limestone,  and  some  other  rocks ;  the  latter  is 
found  in  all  clay  and  slate  rocks.  The  metal  mag- 
nesium bums  with  great  brilliancy  and  is  sometimes 


•4 


SCIENTIFIC  AGRICULTURE. 


used  for  lighting  up  caves  (24).  Aluminium  has 
been  used  to  some  extent  for  ornamental  and  other 
purposes,  but  it  is  so  difficult  and  expensive  to  sep- 
arate from  its  compounds  that  it  has  not  come  into 
general  use. 

43.  Iron  is  a  common  metal  with  which  every- 
body is  familiar.  Its  ores,  such  as  hematite  and 
limonite,  are  abundant,  and  are  used  in  immense 
quantities  for  the  manufacture  of  this  useful  metal. 
It  is  found  in  all  soils  forming  the  coloring  matter 
of  clays,  and  exists  in  a  great  variety  of  minerals. 
Manganese  is  a  metal  very  much  like  iron  in  its  chem- 
ical properties,  but  much  more  difficult  to  separate 
from  its  ores.* 

44.  In  giving  the  composition  of  a  soil  it  is  usual 
to  state  the  percentage  weight  of  the  metallic  oxides 
and  acid-forming  oxides,  as  it  is  known  that  the  ele- 
ments do  not  exist  in  the  soil  in  a  free  state.  The 
process  of  analyzing  a  soil,  that  is,  of  finding  out  its 
constituents,  is  easily  understood  in  theory,  but  to 
perform  the  analysis  requires  some  practice  and 
skill  in  chemical  work.  Such  analyses  are  not  so 
useful  to  the  farmer  as  was  once  supposed,  since  the 
condition  of  the  elements  in  the  soil  has  more  to 
do  with  its  fertility  than  quantity. 

45.  The  following  analysis  of  a  fertile  soil  will 
give  some  idea  of  the  relative  quantity  of  the  con- 
stituents usually  found : 

*  For  a  more  extended  description  of  these  elements  the 
student  is  referred  to  works  on  chemistry. 


SOILS. 


25 


Per  cent. 

Potassium  oxide 0.2 

Sodium  oxide 0.4 

Calcium  oxide,  or  lime 5.9 

Magnesium  oxide,  or  magnesia 0.8^ 

Iron  oxide,  or  ferric  oxide 6.1 

Aluminium  oxide,  or  alumina 5.7 

Manganese  oxide o.i 

Silicon  oxide  (silica) 64.8 

Sulphuric  acid,  or  sulphur  trioxide 0.2 

Phosphoric  acid,  or  phosphorus  pentoxide 0.4^ 

Carbonic  acid,  or  carbon  dioxide 4.0 

Chlorine 0.2 

Organic  matter 9.7 

Loss 1.4 

Total loo.o 

The  proportion  of  some  important  constituents, 
as  potassium  oxide,  phosphoric  acid,  etc.,  is  very 
small,  but  the  smallest  would  amount  to  several  tons 
per  acre. 

46.  Silica,  or  sand,  is  the  chief  substance  in  a  great 
many  soils.  Clay,  a  compound  of  silica  and  alumina 
with  small  quantities  of  other  elements,  is  also  abun- 
dant in  most  soils ;  so  are  lime  and  iron  oxide.  The 
amount  of  organic  matter  is  quite  variable.  In  some 
soils  it  reaches  15  or  20  per  cent.,  while  in  others  it 
is  less  than  i  per  cent.  The  total  absence  of  any 
of  the  constituents  mentioned  above,  except  perhaps 
aluminium  oxide  and  manganese,  would  render  the 
soil  unproductive  for  ordinary  crops.  Those  in  least 
abundance,  as  potassium  oxide  and  phosphoric  acid, 


26  SCIENTIFIC  AGRICULTURE. 

are  most  likely  to  be  deficient,  and  in  such  cases 
they  must  be  supplied  by  the  use  of  fertilizers  or 
manures. 

47.  The  great  quantity  of  sand  in  most  soils  and 
its  presence  in  all  have  suggested  the  propriety  of 
classifying  soils  according  to  the  amount  of  sand 
they  contain,  as  follows  : 

1.  Pure  clay,  from  which  no  sand  can  be  re- 
moved by  washing. 

2.  Strong  clay,  when  the  soil  contains  from  5 
to  20  per  cent,  of  sand. 

3.  Clay  loam,  when  it  contains  from  20  to  40 
per  cent,  of  sand. 

4.  Loam,  from  40  to  70  per  cent,  of  sand. 

5.  Sandy  loam,  from  70  to  90  per  cent,  of 
sand. 

6.  Light  sand,  more  than  90 per  cent,  of  sand. 

It  is  easy  to  classify  soils  in  this  way  by  merely 
washing  out  the  sand  and  weighing  it  (25). 

48.  When  soils  contain  a  large  amount  of  calcium 
carbonate,  they  are  said  to  be  calcareous,  or  marly ; 
and,  when  a  very  large  percentage  of  organic  matter, 
they  are  said  to  be  peaty,  or  are  called  vegetable 
mold.  The  presence  of  a  large  quantity  of  clay 
makes  a  soil  sticky  when  wet,  and  causes  it  to  hold 
moisture  a  long  time,  hence  such  soils  are  said  fo  be 
heavy ;  a  large  quantity  of  sand  gives  the  opposite 
property,  that  is,  of  not  retaining  moisture,  and 
hence  these  are  said  to  be  light. 

49.  The  soil  proper  is  the  surface  layer  down  to 


THE   COMPOSITION  OF  PLANTS. 


27 


where  a  change  in  the  character  of  the  material  takes 
place,  generally  from  six  to  ten  inches  and  beneath 
this  is  the  sub-soil.  Deep  cultivation  increases  the 
depth  of  the  soil,  and  allows  air  and  moisture  to 
enter,  and  the  roots  of  plants  to  penetrate  farther  in 
search  of  food. 


CHAPTER   III. 

THE   COMPOSITION    OF    PLANTS. 

50.  The  following  ten  elements  are  always  found 
in  plants,  and  are  believed  to  be  absolutely  essential 
to  their  growth  : 


Non-metallic. 

Metallic. 

1.  Carbon. 

7.  Potassium. 

2.  Hydrogen. 

8.  Calcium. 

3.  Oxygen. 

9.  Magnesium, 

4.  Nitrogen. 

10.  Iron. 

5.  Sulphur. 

6.  Phosphorus. 

Four  others,  sodium,  manganese,  silicon,  and 
chlorine,  are  generally  found,  and  in  marine,  or  sea 
plants,  iodine  and  bromine.  Traces  of  fluorine  have 
also  been  found,  and  sometimes  minute  quantities  of 
/ithium,  caesium,  and  rubidium,  and  a  few  other  ele- 
ments. 

51.  A  great  many  analyses  and  experiments  have 
been  made  by  chemists  to  find  out  just  what  ele- 


28  SCIENTIFIC  AGRICULTURE. 

ments  enter  into  the  structure  of  plants,  and  whether 
they  are  all  really  necessary  for  plant-growth.  The 
results  of  these  investigations,  as  given  in  the  last 
section,  show  what  sort  of  food  plants  must  have  in 
order  to  grow.  Aluminium,  an  element  found  in  all 
soils  and  the  base  of  all  clay,  does  not  enter  into 
plants.  As  animals  derive  their  food  from  plants  or 
from  each  other,  the  same  elements,  except  silicon, 
enter  into  the  composition  of  both. 

52.  If  a  plant  be  heajted  up  to  the  boiling-point 
of  water,  it  loses  a  large  part  of  its  weight  by  the 
escape  of  water  which  it  contains,  and  becomes  dry. 
In  turnips  and  cabbages,  nine-tenths,  and  in  potatoes 
three-fourths  of  their  weight  is  water  which  can  be 
driven  off  by  heat.  Even  in  cured  hay  and  fodder, 
from  one-sixth  to  one-tenth  is  water.  If  the  dried 
plant  be  exposed  to  a  red  heat,  it  will  take  fire  and 
the  greater  part  be  consumed.  The  small  portion 
left  is  called  the  ash,  and  is  generally  a  fine  white 
or  gray  powder  (26). 

53.  The  portion  of  a  plant  that  burns  is  chiefly 
carbon  combined  with  some  hydrogen  and  oxygen, 
and  a  little  nitrogen.  These  four  elements  are  some- 
times called  organic  elements,  because  they  form  by 
far  the  larger  part  of  organic  bodies.  In  the  process 
of  combustion,  while  these  elements  disappear,  it 
must  not  be  supposed  that  they  are  destroyed.  They 
merely  enter  into  new  combinations  with  the  oxygen 
of  the  air,  forming  chiefly  carbon  dioxide  and  watery 
vapor,  which  float  off  unseen  in  the  atmosphere. 


THE   COMPOSITION  OF  PLANTS. 


29 


54.  When  plants  are  burned  with  free  access  of 
air,  the  sulphur  and  phosphorus  are  oxidized,  and 
remain  in  the  ash  with  the  metals.  Chlorine  and 
silicon  are  also  found  in  the  ash.  This  ash,  or  inor- 
ganic matter,  varies  in  quantity  from  about  one-half 
to  one  per  cent,  in  some  kinds  of  wood  to  from 
15  to  18  per  cent,  in  tobacco.  The  following  table 
shows  about  the  average  percentage  of  ash  in  a 
number  of  vegetable  products  : 

Percentage  of  Ash  in  Dried  Products. 
Cotton,  lint i.o  j  Red  clover 6.8 

"      seed 8.9  :  Cabbage 8.0 


Wheat,  grain 1.9 

"      straw 5.0 

Indian  com 1.5 


Irish  potatoes 4.3 

Turnips ...  lo.o 

Tobacco 15-18 


The  elements  that  enter  into  the  composition  of 
the  ash  are  given  in  the  following  table : 

Percentage  Composition  of  the  Ash  of  Plants. 


Grain.  '  Straw 


Indian 
com. 


Pntfl- 

toes. 


Potassium  oxide 31-54    ia.i6    37.95    61.60 

Sodium  oxide     2.66      i.oo     3.00      i.oo 

Magnesium  oxide,  or  magnesia. ...     12 .  10 

Calcium  oxide,  or  lime  1     3.14 

Iron  oxide trace. 


Phosphorus  pentoxide,  or  phos-  \  \     o  . 

phoric  acid f     4° -3° 

Sulphur  trioxide,  or  sulphuric  acid.      0.08 

Silicon  dioxide,  or  silica j     x  .88 

Chlorine o.io 


4.oO|  7.50  5.00 
6.82  3-40  2.40 
1.02      0.40      0.85 

3. 20;   44.80    17.67 

5.78  1.50  6  25 
I.oo 
2.23 


65-34'     1-45 
o  60  trace. 


Red  clo- 

Tobac- 

ver hay. 

co.* 

31.86 
2.16 

32-63 
3.8T 

12.16 

12  10 

31-0? 
0.66 

40.15 

9.00 

3-74 

3.03 
6.71 
3-33 

4.02 
2.6g 
0.86 

100.00  100.00  100.00  100.00  100.00  100.00 


*  Average  of  several  analyses  of  Kentucky  tobacco  made  in 
the  laboratory  of  Vanderbilt  University  by  Messrs.  Hobbs  and 
Wooldridge. 


3° 


SCIENTIFIC  A  GRICUL  TURE. 


55.  The  elements  heretofore  mentioned  as  form- 
ing the  material  of  plants  are  sometimes  called  ulti- 
mate elements,  because  they  are  the  simplest  forms 
of  matter  into  which  plants  can  be  separated,  or  re- 
solved. What  are  called  the  proximate  elements, 
or  principles,  are  compound  substances,  such  as 
starch,  sugar,  gum,  oil,  cellulose,  or  woody  fibre,  etc. 
While  there  are  a  large  number  of  these,  each  spe- 
cies of  plant  having  its  peculiar  principle,  the 
greater  number  can  be  included  under  the  follow- 
ing groups. 

56.  Amylaceous  and  saccharine  substances, 
such  as  starch,  sugar,  cellulose,  or  woody  fibre,  and 
gum.  These  are  composed  of  only  three  elements, 
carbon,  hydrogen,  and  oxygen.  The  woody  fibre,  or 
cellulose,  forms  the  greater  part  of  many  plants,  and 
usually  consists  of  small  tubes  sticking  to  each  other. 
Cotton  fibre  is  nearly  pure  cellulose.  It  is  contained 
in  all  plants,  in  the  stems,  leaves,  roots,  and  seeds. 
It  has  the  same  elements  in  the  same  proportion 
as  starch,  and  differs  in  these  respects  very  slightly 
from  sugar.  It  can  be  converted  into  one  kind  of 
sugar,  glucose,  by  boiling  with  dilute  sulphuric 
acid, 

57.  Pectose  substances,  like  the  jellies  and 
pulp  of  fruits,  and  of  some  roots,  as  the  turnip,  beet, 
and  onion.  These  substances  are  closely  related  to 
woody  fibre,  and  are  easily  changed  into  it  by  the 
plant. 

58.  Vegetable  acids,  such  as  tartaric  acid  found 


THE   COMPOSITION  OF  PLANTS.  31 

in  grapes,  citric  acid  in  lemons,  and  malic  acid  in 
apples.  These  vegetable  acids  are  numerous,  but 
all  have  the  same  elements,  carbon,  hydrogen,  and 
oxygen,  that  are  found  in  sugar. 

59.  Fats  and  oils,  such  as  are  found  in  olives, 
cotton-seed,  flax-seed,  etc.  These  are  composed  of 
the  same  elements  as  sugar,  but  have  proportionally 
less  oxygen.  Turpentine,  resin,  and  different  kinds 
of  wax,  are  included  in  this  group. 

60.  Albuminoid,  or  protein  bodies,  which  dif- 
fer from  the  group  mentioned,  in  having  nitrogen 
as  a  constituent,  and  in  some  cases  sulphur  and 
phosphorus.  Albumen  is  found  nearly  pure  in  the 
white  of  an  egg,  and  a  similar  substance  is  contained 
in  the  juices  of  plants.  The  term  "  albumen  "  is  used 
by  botanists  to  mean  any  nutritive  material  found  in 
the  seeds  of  plants  without  reference  to  its  chemical 
composition.  Chemists  apply  the  word  only  to  sub- 
stances containing  nitrogen,  and  in  this  sense  it  is 
here  used.  Gluten,  a  sticky  substance  found  in 
flour,  belongs  to  this  class,  and  vegetable  casein, 
similar  to  the  white  curd  of  milk,  found  in  legu- 
minous plants,  such  as  the  pea  and  bean. 

61.  Notwithstanding  the  great  variety  of  these 
proximate  principles,  and  their  great  difference  in 
physical  and  chemical  properties,  they  are  composed 
of  only  a  few  elements.  A  knowledge  of  their  chemical 
constitution  has  very  greatly  simplified  the  changes 
which  take  place  in  the  growth  and  maturity  of  plants, 
and  shown  that  a  very  slight  alteration  in  chemical 


32 


SCIENTIFIC  AGRICULTURE. 


constitution  will  convert  a  disagreeable  or  tasteless 
fruit  into  one  that  is  sweet  and  delicious. 

62.  Starch  and  sugar  differ  from  each  other  very 
slightly  in  the  number  and  proportion  of  their  con- 
stituent elements,  while  starch,  cellulose,  and  gum 
are  the  same  in  these  respects.  How  the  internal 
structure  or  arrangement  of  these  elements  causes  a 
change  in  properties,  we  do  not  know.  Starch  forms 
the  larger  portion  of  the  seeds  of  most  plants,  and 
especially  of  those  used  as  food.  Wheat,  corn,  rice, 
and  potatoes,  when  dry,  are  about  two-thirds  starch. 

63.  Grape-sugar  differs  from  starch  by  one  equiva- 
lent of  water,  that  is,  by  the  addition  of  a  little  water 
chemically  combined,  starch  becomes  sugar.  This 
change  takes  place  in  seeds  to  some  extent  in  the 
process  of  sprouting,  and  is  taken  advantage  of  in  the 
manufacture  of  beer  and  whisky  from  barley  and 
corn.  A  lock  of  cotton,  or  even  some  sawdust,  can 
be  changed  into  sugar  suitable  for  manufacturing  al- 
cohol by  dissolving  it  in  strong  sulphuric  acid,  dilut- 
ing with  water,  and  boiling  for  some  time. 

64.  Every  green  leaf  is  a  tiny  laboratory,  where 
by  the  aid  of  the  sun's  rays  those  changes  are  made 
which  give  us  wood,  and  starch,  and  sugar,  and  gluten, 
and  gum.  To  make  these  the  plant  uses  carbon  di- 
oxide and  ammonia,  and  water  and  other  substances, 
which  enter  the  plant  as  food. 

65.  The  following  table  gives  the  composition  of 
various  crops : 


THE   COMPOSITION  OF  PLANTS. 


33 


Grasses  (hay) 15.0 

Red-clover  hay 15.0 

Wheat 15.0 

Oats I  14.0 

Indian  com 14.5 

Buckwheat <  14.0 

Rye I  16.0 

Rice 14.0 

Cotton-seed I  6.6 

Potatoes. I  75.5 


Alba- 
tnln- 
oids. 


9.4 
14. 


Non-ni- 
trozen- 
ized  ex- 
tractive 
matter. 


Woody 
fibre. 


38.8 
37-3 


28.S 
24.8 

5  o 
9.0 

5-2 

12. 0 
8.0 

3-5 

7-3 
3.1 


5-7 
S-7 
I  7 
3-0 
1.9 
2.3 
i.o 
0.7 
9.0 
1.0 


dd.  The  ash  constituents,  though  small  and  vari- 
able in  quantity,  are  of  prime  importance  in  the 
growth  of  the  plant ;  and  just  here  we  find  the  whole 
theory  of  fertilizing.  The  moisture  and  volatile  com- 
pounds formed  during  combustion  float  off"  unseen 
in  the  air  when  a  plant  is  burned  or  decays,  and,  by 
this  same  air  where  these  compounds  always  exist, 
they  are  carried  to  other  plants  and  serve  as  proper 
food,  while  the  ash  constituents  can  not  be  thus  trans- 
ported. Every  plant  removed  from  the  soil  carries 
with  it  the  elements  of  this  ash,  and,  as  some  of  these 
elements  exist  in  minute  quantities,  the  soil  is  sure 
to  become  exhausted  where  means  are  not  used  to 
have  them  restored. 

67,  The  old  system  of  carrying  away  and  never 
restoring  these  necessary  elements  has  well  been 
called  by  Liebig  a  system  of  spoliation.  Some 
elements,  such  as  iron  and  silicon,  and,  in  mmy  soils, 
calcium  and  sodium,  are  so  abundant  that,  practically, 
they  may  never  become  deficient,  and  yet  they  may 


34 


SCIENTIFIC  AGRICULTURE. 


not  be  in  a  condition  to  be  readily  used  as  food  by  the 
plant.  To  remedy  this  condition,  either  mechail' 
ical  means  must  be  used,  such  as  repeated  plow^ 
ing,  deep  and  thorough,  to  bring  about  exposure  to 
air,  and  rain,  and  sunshine,  and  frost ;  or  chemical 
means,  as  the  application  of  lime  and  various  salts 
which  supply  food  directly,  or  which  exert  a  decom- 
posing action,  and  thus  prepare  the  food  which  al- 
ready exists  in  the  soil  and  render  it  suitable  for  use. 

68.  Phosphorus  and  potassium,  which  are  gen- 
erally in  minute  quantities,  as  well  as  other  elements 
when  deficient,  must  be  supplied,  or  the  vigorous 
growth  of  plants  whose  structure  requires  these  ele- 
ments— and  thio  includes  all  of  our  valuable  crops — is 
an  utter  impossibility.  As  well  might  the  carpen- 
ter dispense  with  nails  in  the  construction  of  a  house, 
or  the  tailor  with  thread  in  making  a  coat,  as  the 
farmer  dispense  with  these  essential  elements  in  the 
growth  of  his  crop. 

69.  As  soils  are  of  great  variety,  their  composition, 
or  character,  should  be  determined,  and  the  deficien- 
cy pointed  out,  if  any  exists,  before  an  attempt  be 
made  to  remedy  the  defect.  While  chemistry  teaches 
the  farmer  the  cause  of  the  exhaustion  of  his  soil  and 
shows  how  this  can  be  prevented,  it  must  not  be  held 
responsible  for  the  failures  resulting  from  the  use  of 
the  many  mixtures  which  are  sold  under  various 
names  as  fertilizers. 

70.  The  means  used  for  furnishing  plants  with 
the  elements  necessary  for  their  growth,  that  is,  for 


THE  ATMOSPHERE. 


35 


keeping  a  soil  fertile,  whether  mechanical  or  chemi- 
cal, must  be  guided  by  sound  judgment.  While  prac- 
tical observation  and  experience  teach  us  that  lands 
do  wear  out  by  continued  cultivation  and  removal 
of  crops,  chemistry  explains  the  cause,  and  points  out 
the  remedy.  This  may  be  by  the  purchase  of  con- 
centrated fertilizers,  or  by  the  use  of  such  fertilizing 
materials  as  already  exist  or  can  be  produced  on 
every  farm.  This  subject  will  be  discussed  in  a  sub- 
sequent chapter. 

CHAPTER   IV. 

COMPOSITION  AND   PROPERTIES  OF   THE  ATMOSPHERE. 

71.  The  atmosphere  from  which  plants  obtain  a 
large  portion  of  their  food  is  a  mixture  of  oxygen  and 
nitrogen  in  the  proportion  of  about  one-fifth  of  the 
former  to  four-fifths  of  the  latter,  with  a  small  quan- 
tity of  carbon  dioxide,  a  trace  of  ammonia,  a  vari- 
able quantity  of  watery  vapor,  and  traces  of  a  few 
other  gases  resulting  from  combustion  and  decay 
Its  composition  by  volume  may  be  stated  as  follows 

Nitrogen 77.95 

Oxygen 20.61 

Watery  vapor 1.40 

Carbon  dioxide .' 0.04 

Ammonia ) 

Hydrogen  carbide . .  ) 

,  (  Hydrogen  sulphide.  ) 

In  towns  -I  ^.  ,  ,  . ,         f- traces 

(  bulphurous  oxide. . .  \ 

Total 100.00 


36  SCIENTIFIC  AGRICULTURE. 

72.  These  constituents,  though  gaseous  and  in- 
visible, can  be  separated  and  measured  by  the  chem- 
ist as  surely  and  definitely  as  the  farmer  can  mea- 
sure his  corn  and  wheat,  or  the  planter  weigh  his 
cotton  and  tobacco.  Two  of  these,  carbon  dioxide 
and  ammonia,  though  in  very  small  quantities,  are 
sufficient  for  the  ordinary  growth  of  plants.  They 
are  all  so  nicely  intermingled,  so  uniformly  mixed, 
that  dry  air,  no  matter  where  collected,  is  found  to 
possess  essentially  the  same  composition. 

73.  Watery  vapor,  as  above  stated,  is  a  variable 
constituent  of  the  atmosphere.  It  rises  continually 
from  the  surface  of  the  land,  as  well  as  from  every 
lake,  and  river,  and  ocean,  and  comes  to  us  again  in 
gentle  showers  which  the  cool  currents  of  air  con- 
dense, or  in  dew-drops  which  settle  by  night  on  leaf 
and  flower.  Beautifully  harmonious  are  the  laws 
and  operations  of  nature,  and  especially  that  law  by 
which  the  vapor  of  water  so  gently  and  continuously 
ascends  from  the  earth's  surface  and,  condensing, 
falls  to  be  again  vaporized  after  it  has  performed  its 
part  in  the  support  of  animal  and  vegetable  life. 

74.  The  study  of  chemistry  has  revealed  the  part 
that  each  of  these  constituents  of  the  atmosphere 
performs  in  the  economy  of  nature.  Nitrogen  is 
negative  in  its  character,  being  indifferent  toward 
entering  into  combination  with  other  elements,  while 
oxygen  is  active  and  energetic  in  supporting  com- 
bustion, and  in  sustaining  animal  life.  Our  bodies, 
like  stoves,  are  consumers  of  carbon  and  oxygen,  and 


THE  ATMOSPHERE. 


31 


produce  in  a  similar  manner  the  gas  known  as  car- 
bonic acid,  or  carbon  dioxide.  This  gas  is  poisonous 
to  animals  when  it  exists  in  any  considerable  quan- 
tity in  the  air,  but  is  absolutely  essential  to  the 
growth  of  plants. 

75.  Carbon  dioxide  consists  of  carbon  and  oxy- 
gen, and  is  generated  in  all  cases  of  ordinary  com- 
bustion, in  putrefaction,  fermentation,  and  decay. 
It  is  also  a  product  of  respiration,  and  would  soon 
accumulate  in  sufficient  quantity  to  destroy  animal 
life,  were  it  not  for  the  fact  that  it  is  absorbed  by  the 
leaves  of  trees  and  plants,  there  deprived  of  its  car- 
bon, and  pure  oxygen  restored  to  the  air  whence  it 
came  (28). 

76.  Every  one  has  observed  the  soft,  porous  tex- 
ture of  the  under  surface  of  the  leaves  of  plants; 
through  these  pores  the  carbon  dioxide  is  inhaled  as 
it  floats  in  the  atmosphere,  and  under  the  influence 
of  sunlight  the  process  of  digestion  takes  place  with- 
in the  plant  whereby  the  carbon  is  retained  as  food, 
and  the  oxygen  exhaled,  thus  preserving  the  purity 
of  the  air. 

77.  The  relative  amount  of  carbon  dioxide  in  the 
atmosphere  is  only  about  one  twenty-fifth  of  one  per 
cent.,  and  yet  it  is  enough  for  the  purposes  of  vegeta- 
tion. A  distinguished  chemist  says,  "  The  gigantic 
trees  which  adorn  the  forests  of  tropical  regions  with 
the  dense  pine  woods  of  more  northern  zones,  and 
the  abundant  though  less  conspicuous  vegetation 
of  temperate  climes,  all  derive  their  stock  of  carbon 


38  SCIENTIFIC  AGRICULTURE. 

from  this  small  but  essential  constituent  of  the  at- 
mosphere." 

78.  Ammonia  exists  in  the  air  in  even  more  mi- 
nute quantities  than  carbon  dioxide,  so  minute  that 
only  the  most  delicate  tests  can  indicate  its  pres- 
ence, and  the  most  sensitive  balance  would  not  be 
affected  by  the  quantity  in  a  room  of  ordinary  size, 
and  yet  it  is  of  essential  value  to  all  kinds  of  vege- 
tation. 

79.  A  close  study  of  the  nature  and  composition 
of  the  atmosphere  shows  that  it  is  admirably  adapted, 
by  its  physical  and  chemical  properties,  to  the  wants 
of  animals  and  plants.  "  It  conveys  to  them  their 
nourishment  and  life  ;  it  tempers  the  heat  of  summer 
with  its  breezes;  it  binds  down  all  fluids,  and  pre- 
vents their  passing  into  a  state  of  vapor ;  it  supports 
the  clouds,  distills  the  dew,  and  waters  the  earth  with 
showers ;  it  multiplies  the  light  of  the  sun,  and  diffuses 
it  over  earth  and  sky ;  it  feeds  our  fires,  turns  our 
machines,  wafts  our  ships,  and  conveys  to  the  ear  all 
the  sentiments  of  language  and  all  the  melodies  of 
music." 

80.  Science  teaches  us  that  Infinite  Wisdom  has 
shown,  in  these  invisible  atmospheric  agencies  at 
work  around  us,  the  same  skill  and  benevolence, 
the  same  goodness  and  power,  as  in  the  more  mani- 
fest displays  of  divine  energy.  Silently  but  surely 
they  accomplish  their  appointed  work  of  contribut- 
ing directly  to  the  nutrition  of  organic  bodies,  and 
by  their    action    upon  solid    substances  continually 


THE   SOURCES  OF  PLANT-FOOD. 


39 


prepare  material  to  take  its  proper  place  in  the  build- 
ing up  of  animal  and  vegetable  structures. 

8i.  The  atmosphere  acts  upon  both  organic  and 
inorganic  matter  so  as  to  reduce  it  to  simpler  forms- 
As  soon  as  an  animal  or  plant  dies,  by  contact  with 
the  air  its  elements  quietly  but  surely  undergo  a 
change,  recombining  to  form  new  and  simpler  com- 
pounds capable  of  entering  again  into  organic  bodies. 

82.  Knowing  the  composition  of  the  soil,  of 
plants,  of  air,  we  are  prepared  to  study  their  relations 
and  the  laws  of  growth  and  development  in  plants. 


CHAPTER  V. 

THE   SOURCES   OF    PLANT-FOOD    AND    HOW  OBTAINED. 

83.  The  earth  and  atmosphere  are,  of  course,  the 
only  possible  sources  of  food  for  plants,  but  the  in- 
teresting questions  arise,  What  portion  of  food  does 
each  furnish  ?  and  how  is  it  taken  up  and  used  by  the 
plant  ?  If  we  include  hydrogen,  which  is  one  of  the 
elements  in  watery  vapor  and  in  ammonia,  there  are 
four  elements  in  air,  viz.,  oxygen,  nitrogen,  carbon, 
and  hydrogen.  A  great  many  experiments  have  been 
made  to  find  out  whether  these  four  elements  enter 
directly  from  the  air  into  plants,  through  the  leaves, 
or  are  taken  in  by  the  roots  from  the  soil. 

84.  Carbon,  the  most  abundant  element  in  or- 
ganic substances,  cannot  enter  the  plant  in  a  pure 


40 


SCIENTIFIC  AGRICULTURE. 


State,  as  it  is  perfectly  insoluble.  In  the  gaseous 
form,  as  carbon  dioxide,  it  is  absorbed  in  large  quan- 
tities by  the  leaves,  and  it  als^  enters  through  the 
roots.  By  the  action  of  sunlight  this  gas  is  decom- 
posed in  the  green  leaf,  the  carbon  retained,  and  the 
oxygen  restored  to  the  air.  This  change  cannot  take 
place  without  the  influence  of  sunlight,  and  hence 
plants  grow  much  more  rapidly  in  the  daytime  than  at 
night.  It  is  believed,  by  those  who  have  studied  the 
subject  closely,  that  all  the  carbon  contained  in  farm 
crops  is  derived  from  the  atmosphere. 

85.  Hydrogen  and  oxygen  enter  in  the  form 
of  water  through  the  roots,  and  carry  with  them  the 
various  soluble  matters  of  the  soil  that  are  needed 
for  growth.  Hydrogen  also  enters  in  the  form  of 
ammonia,  which  is  a  compound  of  nitrogen  and  hy- 
drogen, and  as  hydrogen  compounds  formed  by  the 
decomposition  of  organic  matters  in  the  soil.  In  the 
same  manner  oxygen,  in  combination  with  carbon 
and  with  hydrogen  and  other  elements,  is  absorbed 
in  large  quantities. 

86.  Nitrogen  is  also  taken  in  as  food  by  both 
leaves  and  roots,  but  always  in  combination.  This 
element  forms  nearly  four-fifths  of  the  atmosphere, 
and  yet,  as  free  nitrogen,  it  does  not  contribute  in 
the  least  to  vegetable  growth.  The  whole  of  the 
nitrogen  is  obtained  from  compounds  of  ammonia 
and  from  nitrates. 

87.  Plants  contain  very  little  nitrogen,  generally 
from  one  half  to  three  per  cent.     This,  however,  is 


THE   SOURCES  OF  PLANT-FOOD. 


41 


as  necessary  as  those  elements  that  enter  largely 
into  their  composition.  Gne  ton  of  hay  contains 
about  thirty  pounds  of  nitrogen,  a  small  quantity 
proportionally,  but  in  one  hundred  tons  it  amounts 
to  a  great  deal.  The  stimulating  effect  of  guano  and 
similar  manures  is  due  mainly  to  the  nitrogen  they 
contain  in  the  form  of  ammonia  and  its  salts.  While 
the  atmosphere  may  contain  ammonia  enough  to 
meet  the  ordinary  demands  of  vegetation,  it  has  not 
enough  to  supply  the  extraordinary  demand  of  an 
immense  crop  in  a  limited  time. 

88.  The  four  elements  just  mentioned  are  some- 
times called  organic  elements,  because  they  form 
much  the  larger  part  of  all  organic  bodies.  The  re- 
maining constituents,  called  inorganic  elements,  are 
found  in  the  ash  of  plants,  and  are  always  taken 
in  as  soluble  matter  through  the  roots.  The  question 
arises,  In  what  manner .''  Before  answering  this  ques- 
tion, it  will  be  well  to  examine  the  structure  and  use 
of  the  different  parts  of  a  plant. 

89.  The  main  parts  of  a  plant  are  the  root,  the 
stem,  and  the  leaves  (29).  The  root  spreads  through 
the  earth  as  the  stem  does  through  the  air.  The 
seed  contains  an  initial  sl^^k  that  is,  the  beginning 
of  a  stem,  with  food  enoughT^Kart  it  to  growing.  It 
requires  for  germination  or  fir^growth,  air,  warmth, 
and  moisture.  The  moisture  which  is  first  absorbed 
causes  the  seed  to  swell,  oxyg^a^enters,  a  chemical 
change  takes  place  in  the  ele^nts  composing  it 
whereby  the  germ,  or  little  plant,  gradually  enlarges, 


42 


SCIENTIFIC  A  GRICUL  TUHE. 


the  covering  bursts,  and  the  radicle,  or  rootlet,  ap- 
pears, and  buries  itself  in  the  earth,  while  the  little 
stem  or  plumule,  as  it  is  called,  rises  to  the  surface  of 
the  ground  in  search  of  sunlight.  Nature  has  stored 
up  in  the  seed  enough  material  to  supply  the  growth 
thus  far,  but  henceforth  its  food  must  come  from  the 
soil  and  atmosphere.  This,  in  some  mysterious  way, 
through  the  influence  of  sunlight,  it  is  enabled  to 
take  in  and  digest. 

90.  The  root  once  started,  divides  and  subdi- 
vides, sending  out  branches  in  every  direction  and 
hunting  industriously  in  the  soil  for  nourishment, 
while  the  stem  and  leaves  do  the  same  in  the  at- 
mosphere. The  leaves  are  in  some  sense  the  lungs 
of  the  plant,  while  the  roots  are  its  mouths.  The 
length  to  which  the  roots  sometimes  extend  is  as- 
tonishing, and  they  really  seem  to  have  a  kind 
of  instinct  that  guides  them  to  their  proper  food. 
Those  which  find  proper  nourishment  enlarge  and 
multiply  rapidly,  while  those  that  do  not,  die  or  re- 
main undeveloped.  For  a  plant  to  be  thrifty,  it 
must  have  plenty  of  suitable  food,  and  have  it  near 
at  hand.  It  cannot,  like  an  animal,  run  about  in 
search  of  what  it  needs^Hjiigh  it  will  extend  its  roots 
to  a  long  distance  if  ^^^sary  to  get  suitable  mate- 
rial for  growth.  ^^ 

91.  Schubert,  a  German  agriculturist,  made  an 
excavation  in  a  fielj^o  the  depth  of  six  feet,  and  di- 
rected a  stream  of^ater  against  the  vertical  wall  of 
soil  until  it  was  washed  away,  so  that  the  roots  of 


THE   SOURCES  OF  PLANT-FOOD. 


43 


plants  growing  in  it  were  laid  bare.  Roots  were  ex- 
posed in  this  way  in  a  field  of  rye,  also  in  one  of 
beans,  and  in  a  bed  of  garden-peas,  which  were 
found  to  present  the  appearance  of  a  mat  of  white 
fibres  to  a  depth  of  four  feet  from  the  surface  of  the 
ground.  He  found  the  roots  of  winter  wheat  as  deep 
as  seven  feet  in  a  light  sub-soil  forty-seven  days 
after  sowing.  Another  German,  who  has  studied 
the  subject,  calculated  the  total  combined  length 
of  the  roots  of  a  vigorous  barley  plant  in  a  rich 
garden  soil  to  be  one  hundred  and  twenty-eight 
feet,  and  in  a  coarse-grained,  compact  soil  eighty 
feet. 

92.  The  absorbing  surface  of  roots  is  greatly  in- 
creased by  very  small  root-hairs  which  are  lost  as 
the  roctfs  become  old.  It  was  once  supposed  that 
the  ends,  or  tips  of  roots  consist  of  delicate  tissue, 
or  organs  called  "  spongioles,"  through  which  alone 

rption  of  food  takes  place,  but  such  is  not  the 
se  ;  no  organ  or  structure  of  the  kind  exists. 

93.  Agricultural  writers  distinguish  three  kind  of 
roots,  viz.,  soil  roots,  water  roots,  and  air  roots. 
Nearly  aljPI^  our  useful  plants  have  soil  roots  which 
perish  if  kept  for  a  length  of  time  in  air  or  water, 
while  sl^Sfe^ plants,  as  rice  for  instance,  have  roots 
which  ^fXk.  grow  either  in  soil  or  water.  The  com- 
mon mulberry  and  China  tree  will  extend  a  portion 
of  their  roots  down  to  the  bottom  of  a  well  thirty  or 
more  feet  in  depth,  and  mat  over  the  bottom  com- 
pletely, while  the  cornstalk  will  put  out  air  roots  at 


44 


SCIENTIFIC  AGRICULTURE. 


a  joint  above  the  ground,  which  extend  until  they 
reach  and  penetrate  the  soil. 

94.  It  was  once  supposed  that  roots  have  the 
power  of  excretion,  the  reverse  of  absorption,  but 
Johnston  says,  '*  In  the  light  of  newer  investigations 
touching  the  structure  of  roots  and  their  adaptation 
to  the  medium  which  happens  to  invest  them,  we 
may  well  doubt  whether  agricultural  plants  in  the 
healthy  state  excrete  any  solid  or  liquid  matters  from 
their  roots."  The  food  that  enters  a  plant  through 
the  roots  must  be  in  a  state  of  solution.  There  is 
no  doubt  that  plants  have,  to  a  certain  extent, 
the  power  of  selection.  We  know  that  plants  grown 
on  the  same  soil  and  under  the  same  conditions  do 
not  have  the  same  elements  in  equal  proportions. 

95.  From  the  facts  stated  in  reference  to  roots,    • 
the  importance  of  deep,  thorough  preparation  of 
land  before  planting,  and  of  shallow  cultivation  after 
the  crop  has  been  well  started,  is  evident.     Should^ 
the  soil,  however,  become  hard  and  baked,  it  wom^^Bfc 
be  good  policy  to  cultivate  deeply  even  at  the  risk 

of  destroying  rootlets,  which  under  such  circum- 
stances are  necessarily  sickly,  that  new  and  vigorous 
ones  may  put  forth  and  have  mellow  soil  through 
which  to  penetrate.  No  fixed  rule  can  be  laid  down 
to  be  rigidly  followed  in  all  cases.  The  intelligent 
farmer  or  planter  should  be  guided  by  the  indica- 
tions of  the  season,  and  the  condition  of  his  crop,  in 
the  use  of  means  necessary  to  meet  an  emergency. 
Even  the  bird,  though  governed  by  instinct,  modifies 


THE  IMPROVEMENT  OF  SOILS. 


45 


at  times  the  shape  of  its  nest  to  adapt  it  to  peculiar 
surroundings,  and  so  the  farmer  must  use  his  reason 
in  cultivating  his  crop.  He  should  be  guided,  not 
by  "  cast-iron  "  rules,  but  by  correct  principles,  and 
modify  his  mode  of  cultivation  to  suit  each  particu- 
lar case. 


CHAPTER   VI. 

THE    IMPROVEMENT    OF    SOILS. 

96.  Dead  matter  has  no  power  in  itself,  so  far  as 
we  know,  to  change  into  an  organized  structure.  It 
has  the  power,  under  certain  circumstances,  of  form- 
ing crystals  of  great  beauty,  but  in  these  forms  there 
is  no  life.  This  life-principle,  every  seed  or  germ 
has  within  itself,  and  when  called  into  activity  it  un- 
folds the  plant.  Exactly  what  this  life-principle  is, 
we  know  not,  but  we  can  study  the  conditions  of 
plant-growth,  and  explain  to  some  extent  the  changes 
which  take  place  in  the  swelling  of  the  seed  by  heat 
and  moisture,  and  its  partial  decomposition  into 
simpler  forms,  whereby  energy  is  imparted  in  some 
mysterious  way,  suflRcient  to  push  the  rootlet  down- 
ward, and  the  slender  stem  upward  to  the  sunlight. 

97.  The  connection  between  the  rays  of  the  sun 
drunk  in  by  the  leaves  of  plants  and  the  absorption 
of  food  by  their  roots,  the  appropriation  of  this  food 
and  its  assimilation  or  use  in  the  production  of  bark, 
and  wood,  and  leaves,  and  fruit,  has  not  yet  been  ex- 


46  SCIENTIFIC  AGRICULTURE. 

plained,  and  perhaps  never  will  be.  Chemistry,  how- 
ever, has  taught  us  how  to  stimulate  the  process,  and 
has  shown  us  that  there  is  no  change  of  one  element 
into  another,  but  a  simple  use  of  that  which  is  in  reach 
of  the  plant,  whether  it  be  in  the  air  above  or  in  the 
soil  beneath. 

98.  If  it  be  absurd  to  suppose,  as  everybody  must 
admit,  that  one  element  can  change  into  another,  the 
practical  conclusion  follows  that,  to  insure  fertility, 
the  necessary  elements  which  compose  the  particular 
plant  under  cultivation  must  exist  in  the  soil,  or  its 
growth  is  impossible.  As  simple  and  self-evident  as 
this  statement  may  appear,  there  has  ever  been  a 
vague  notion  in  the  minds  of  men  that  nature  has 
some  power  of  changing  elements,  or  of  supplying 
them  as  needed  for  the  growth  of  vegetation. 

99.  It  has  not  been  many  years  since  writers  on 
agriculture  affirmed  that  the  inorganic  constituents 
of  a  good  soil  are  inexhaustible.  Such  statements 
are  contrary  to  the  teachings  of  science  and  of  prac- 
tical experience.  It  is  true,  the  application  of  scien- 
tific principles  in  farming  will  not  in  every  case  pro- 
duce a  good  crop,  because  there  are  conditions  that 
human  agency  cannot  control.  The  wind,  and  rain, 
and  sunshine  are  given  or  withheld  by  a  power 
which  we  cannot  govern,  and  without  whose  favor- 
ing influence  all  our  labor  is  in  vain. 

100.  Science  not  only  determines  the  kind  and 
quality  of  food  which  plants  need,  but  points  out  the 
localities  where  this  food  can  be  obtained,  and  fur 


THE  IMPROVEMENT  OF  SOILS. 


47 


nishes  the  farmer  with  methods  for  preparing,  in  con- 
centrated form,  the  very  elements  which  are  deficient 
in  an  unproductive  soil.  Through  the  influence 
of  its  teachings,  the  manufacture  of  fertilizers  has 
become  one  of  the  great  industries  of  the  world. 
Substances  in  the  highest  degree  offensive,  injuri- 
ous to  health,  and  difficult  to  be  gotten  rid  of, 
have  been  converted  into  merchandise  of  great 
value. 

loi.  The  disposal  of  refuse  matter,  by  putting  it 
to  profitable  use,  is  one  of  the  greatest  results  of 
modern  science.  A  portion  at  least  of  the  sewage  of 
London,  and  other  large  cities  of  the  world,  is  now 
rendered  harmless,  and  inoffensive,  and  even  valua* 
ble  as  an  article  of  trade.  A  perfect  system  of  agri- 
culture requires  that  it  should  all  be  returned  to  the 
soil  whence  it  came,  and  serve  as  food  for  growing 
crops.  The  indestructibility  of  matter,  in  connection 
with  the  correlation  and  conservation  of  energy,  pre- 
sents nature  as  a  grand  system  of  mutually  depen- 
dent parts  which  move  in  a  ceaseless  round  of  univer- 
sal harmony.  It  is  for  science  to  study  the  relation 
of  these  parts,  however  vast  or  minute,  and  teach  us 
how  to  control  their  movements  so  as  to  promote 
the  interests  of  the  human  race.  Much  has  been 
done  in  this  direction,  while  much  remains  to  be 
accomplished. 

I02.  All  truly  scientific  methods  of  improvement 
of  soils  are  founded  on  observation  and  experiment 
and  are  addressed  to  the  reason  and  common  sense 


48  SCIENTIFIC  AGRICULTURE. 

of  intelligent  men.  If  a  soil  has  all  the  constituents 
that  plants  need,  and  in  the  best  possible  condition 
for  use  as  plant-food,  then  such  soil  cannot  be  im- 
proved. If,  however,  one  or  more  constituents  are 
deficient,  or  entirely  absent,  or  not  in  the  best  con- 
dition to  serve  as  plant-food,  then  improvement  is 
not  only  possible,  but  desirable. 

103.  The  means  used  for  the  improvement  of 
soils  are : 

Mechanical,  as  draining,  plowing,  sub-soiling, 
mixing  with  clay,  etc. 

Chemical,  as  manuring  or  fertilizing. 

The  first  changes  the  physical  properties;  the 
second,  the  composition.  When  necessary  constitu- 
ents are  absent  or  deficient,  no  amount  of  draining 
or  sub-soiling  will  secure  a  good  crop. 

104.  The  extensive  and  thorough  system  of  drain- 
ing by  means  of  tiles  or  clay  pipes,  which  is  used 
in  Europe  and  in  some  portions  of  our  own  country, 
is  too  costly  where  land  is  cheap  and  abundant.  In 
such  cases  open  ditches  should  be  used  to  carry  off 
surplus  water.  Intelligent  farmers  understand  very 
well  the  importance  of  removing  excess  of  water  by 
some  sort  of  drainage  that  will  be  least  likely  to  re- 
move the  soil  with  it,  but  unfortunately  they  do  not 
always  put  their  knowledge  into  practice.  Where 
loose  rock  is  convenient,  covered  ditches  with  ten  or 
twelve  inches  of  rock  at  the  bottom  are  easily  made, 
and  form  excellent  drains.  Deep  plowing  and  sub- 
soiling  are  means  of  draining,  to  a  limited  extent, 


THE  IMPROVEMENT  OF  SOILS.  4Q 

but  cannot  be  substituted  for  ditching  in  wet,  swampy 
lands. 

105.  The  advantages  of  drainage  are  numerous, 
of  which  may  be  mentioned  the  following: 

(i.)  It  makes  the  soil  warmer.  The  evaporation 
of  water  from  any  surface  is  cooling.  The  heat  of 
the  sun  falling  on  a  wet  soil  is  taken  up  in  convert- 
ing the  water  into  vapor,  and  does  not  reach  the  roots 
of  the  plant. 

(2.)  It  keeps  the  plant  food  from  becoming  too 
much  diluted,  and  leaves  it  in  a  concentrated  form 
for  absorption  by  the  plant. 

(3.)  It  gives  free  access  of  air  to  the  roots  of 
plants.  Water  not  only  keeps  out  the  air,  but 
drowns  or  destroys  the  soil  roots. 

(4.)  It  aids  in  bringing  about  a  proper  decompo- 
sition of  organic  matter,  and  preventing  the  forma- 
tion of  organic  acids  that  are  hurtful.  Swampy  lands 
which  are  generally  sour  and  unproductive  for  valu- 
able crops  are  rendered  productive  by  draining. 

106.  Deep  plowing  and  sub-soiling  not  only  as- 
sist in  draining  the  soil,  but  also  render  it  better  able 
to  stand  a  drought.  The  surplus  water  of  heavy  rains 
can  sink  down  without  washing,  while  the  capillary 
action  of  a  thoroughly  pulverized  soil  draws  mois- 
ture from  a  greater  depth  in  time  of  drought,  and  the 
roots  penetrate  more  easily  beyond  the  influence  of 
the  sun's  rays  and  find  abundant  food,  while  air  can 
also  reach  a  lower  depth  more  readily  and  exercise 
its  disintegrating  effect. 

4 


50 


SCIENTIFIC  AGRICULTURE. 


107.  Deep  plowing  also  brings  new  earth  to  the 
surface,  and  forms  a  deeper  soil,  altering  its  physical 
and  chemical  properties  and  promoting  the  growth 
of  vegetation.  Should  the  sub-soil  be  less  fertile 
than  the  surface,  which  is  generally  the  case,  care 
should  be  taken  not  to  bring  much  of  it  to  the  sur- 
face during  any  one  season.  After  the  soil  has  been 
deepened  sufficiently,  the  sub-soil  should  only  be 
stirred  by  means  of  the  sub-soil  plow. 

108.  A  very  economical  and  effective  method  of 
sub-soiling  is  to  run  a  plow  with  a  long  narrow  shovel 
immediately  behind  the  common  turn-plow.  The 
shovel  can  be  made  by  a  common  blacksmith,  and 
be  easily  repaired.  The  expense  of  sub-soiling  can 
thus  be  made  very  light,  while  the  advantages,  espe- 
cially in  heavy  soils,  are  sure  to  be  recognized  after 
a  thorough  trial. 

109.  There  are  other  mechanical  means  of  im- 
provement, such  as  the  mixing  of  stiff  clays  with 
light,  sandy  soils,  and  the  opposite,  which  are  prac- 
tised with  advantage  in  thickly  populated  countries, 
but  which  cannot  be  profitably  employed  by  us  in 
the  cultivation  of  wheat,  corn,  cotton,  and  tobacco. 
The  main  object  is  to  secure  the  greatest  amount 
of  improvement  at  the  least  expense.  An  unset- 
tled feeling  frequently  prevails  among  farmers  and 
planters  in  a  new  country  which  operates  strongly 
against  anything  like  permanent  improvement,  and 
tends  to  produce  careless  cultivation  and  rapid  ex- 
haustion of  the  soil.     The  abundant  supply  of  new 


THE   USE  OF  MANURES. 


5^ 


lands  in  the  far  West  tends  to  produce  the  same  re^ 
suit. 

no.  It  is  a  narrow-sighted  policy  that  opposes 
thorough  cultivation  and  the  use  of  fertilizers,  on 
the  ground  that  this  may  be  the  last  crop,  and  such 
investments  of  labor  and  capital  can  not  be  remu- 
nerative the  first  year.  Thorough,  cultivation  is 
always  proper.  Whether  fertilizers  should  be  used, 
as  well  as  what  kinds,  depends  upon  circumstances, 
which  will  be  discussed  in  the  next  chapter. 


CHAPTER  VII. 

THE   USE   OF   MANURES,    OR   FERTILIZERS. 

III.  The  chemical  improvement  of  soils  em- 
braces the  use  of  fertilizers,  or  manures,  the  applica- 
tion of  which  depends  on  the  following  well-estab- 
hshed  principles : 

1.  Plants  derive  an  essential  part  of  their  food 
from  the  soil.  This  includes  all  the  inorganic  ele- 
ments found  in  the  ash,  and  a  variable  quantity  of 
those  organic  elements  which  volatilize  when  the 
plant  is  burned. 

2.  Different  plants  require  a  special  supply  of 
different  kinds  of  inorganic  food,  or  the  same  kinds 
in  different  proportions,  which  must  be  contained  in 
the  soil. 

3.  Some  soils  have  a  deficiency  of  plant-food 


Sa 


SCIENTIFIC  AGRICULTURE. 


which  must  be  supplied  before  particular  plants  can 
grow.  The  food  may  be  in  the  soil,  but  not  in  a 
condition  to  be  appropriated  by  the  plant. 

112.  Soils  may  be  naturally  deficient  in  impor- 
tant constituents,  or  they  may  have  become  so  by 
long-continued  cultivation  and  removal  of  crops. 
In  such  cases,  improvement  is  effected  by  the  addi- 
tion of  a  suitable  fertilizer,  or  manure. 

113.  The  continued  removal  of  crops  is  sure  to 
produce  exhaustion.  The  following  table. shows  the 
quantity  and  composition  of  the  ash  contained  in 
one  English  ton  (2,240  pounds)  of  hay  of  different 
kinds,  and  which  is  carried  off  when  the  hay  is  taken 
from  the  farm  (the  numbers  represent  pounds) : 


Potash 

Soda 

Lime 

Magnesia 

Oxide  of  iron . . . 
Sulphuric  acid. . 
Phospihoric  acid 

Chlorine 

Silica 


Italian  ry*- 
gnus  hay. 


17 

7  , 

3 

I 

8iJ^ 


138 


Clover  hay. 

Red. 

White. 

26 

24K 

3^ 

^0% 

55J^ 

45}^ 

i7J^ 

14 

r'A 

z'A 

(>% 

12% 

10 

20 

4 

5 

5 

6 

129K 

141K 

Lacerne  hay. 


30  , 
13^ 

% 
9 


2"J^ 


114.  Animal  products  also  remove  valuable  con- 
stituents, and  in  large  quantities,  as  can  be  seen  from 
the  following  table,  which  is  based  upon  the  experi- 
ence of  Messrs.  Lawes  and  Gilbert,  two  noted  Eng- 
lish agriculturists : 


THE    USE   OF  MANURES, 
•  Composition  of  Animal  Exports  from  a  Farm. 


Si 


Fat  ox,  per  i,ooo  lbs.  fasted 
live  weight  ....    

Fat  sheep,  per  i,ooo  lbs.  fast-  _ 
ed  live  weight ( 

Fat  pig,  per  i,ooo  lbs.  fasted  I 
live  weight j 

Milk,  i,ooo  lbs 

Wool,  unwashed,  i,ooo  lbs 


Nitrogen. 


Lbs. 
23 -13 
19.60 

17-57 

5-25 
73.00 


Phcphorlc 
acid. 


Lbt. 
16.53 

IX. 29 

6.92 

2.03 
1. 00 


Lbt. 
1.84 

1-59 
1.48 

1.80 
40.00 


Umo. 


Magne. 


Lbs. 
19.20 

12.80 

6.67 
1.56 


Lbs. 
0.63 

0-53 

°-3S 
0.16 
0.70 


By  "  fasted  "  is  meant  that  the  animals  were  killed 
when  their  digestive  organs  were  empty,  or  nearly 
so. 

115.  The  rapidity  of  exhaustion  will  depend  upon 
the  kind  of  products  removed.  Some  writers  assert 
that  the  amount  of  plant-food  in  good  soils  is  so 
great,  that  practically  they  can  not  be  exhausted,  but 
the  experience  of  farmers  proves  the  contrary.  Good 
crops  of  wheat  have  been  grown  on  the  same  soil  for 
a  number  of  years  without  manures,  but  careful  ex- 
periments show  that  there  is  a  gradual  falling  off  in 
the  yield. 

116.  The  fertilizers,  or  manures  used  for  improv- 
ing soils  and  restoring  fertility,  may  be  divided  into 
three  kinds,  vegetable,  animal,  and  mineral. 

117.  As  every  decaying  plant  contains  all  the 
constituents  necessary  for  the  growth  of  a  similar 
plant,  of  course  it  furnishes  a  good  fertilizer.  Vege- 
table substances,  such  as  clover,  pea-vines,  etc.,  are 
sometimes  plowed  in  with  great  benefit  to  the  soil. 
They  not  only  furnish  material  properly  prepared  as 


54 


SCIENTIFIC  A  GRICUL  TURE. 


available  food,  both  organic  and  inorganic,  blit  they 
are  also  highly  useful  in  making  stiff  lands  mellow 
and  porous,  and  light  soils  retentive  of  moisture. 

1 1 8.  Cornstalks  laid  in  a  furrow  and  the  earth 
bedded  upon  them,  and  even  weeds  when  turned 
under,  produce  a  fine  mechanical  effect  on  stiff  lands 
apart  from  their  value  as  chemical  manures.  Whether 
green  or  dry,  these  vegetable  substances  soon  under- 
go decomposition,  and  give  up  their  constituents  as 
food  to  growing  plants. 

119.  Cotton-seed  is  one  of  the  best  and  most  ener- 
getic of  this  class  of  fertilizers.  It  contains  a  great 
deal  of  nitrogen,  which  has  a  wonderful  effect  in  stim- 
ulating vegetable  growth.  Leaves,  and  all  sorts  of 
vegetable  matter,  can  be  profitably  used,  which,  as  a 
top-dressing,  produce  warmth,  and  as  they  decay 
furnish  valuable  plant-food. 

120.  The  large  amount  of  cotton-seed  produced 
in  the  South  has  caused  special  attention  to  be  called 
of  late  years  to  its  value  and  to  the  best  method  of 
using  it  as  a  fertilizer.  Like  other  seeds  it  is  rich 
in  potash  and  phosphoric  acid,  two  important  con- 
stituents of  a  fertile  soil,  which  are  generally  in  such 
limited  quantities  that  in  the  process  of  removal  of 
crops  they  are  the  first  to  become  deficient.  Cotton 
lint  contains  only  about  i  per  cent,  of  ash  or  mineral 
matter,  while  the  seed  contains  about  9  per  cent.  In 
a  bale  of  cotton,  the  yield  of  say  1,700  pounds  of  seed- 
cotton,  we  have  only  five  pounds  of  mineral  matter 
in  the  lint,  and  one  hundred  and  eight  in  the  seed 


THE    USE   OF  MANURES. 


55 


The  removal  of  the  seed,  therefore,  is  more  than 
twenty-one  times  as  exhaustive  of  mineral  matter  as 
the  removal  of  the  lint. 

121.  If  the  seed  be  returned  to  the  soil,  there  is 
no  marketable  crop  less  exhaustive  of  mineral  mat- 
ter than  cotton,  but  if  the  seed  be  permanently  re- 
moved the  result  is  quite  different.  In  view  of  the 
importance  of  restoring  this  valuable  substance  to  the 
soil,  the  question  arises,  How  can  it  be  done  with  the 
greatest  advantage  to  succeeding  crops.?  Like  all 
organic  substances  it  must  undergo  decomposition 
before  it  can  serve  as  plant-food.  If  this  decom- 
position be  effected  in  a  heap  without  mixing  with 
earthy  matter,  the  ammonia  generated  will  mostly 
escape.  This  escaping  ammonia  is  the  most  ener- 
getic stimulant  known,  and  should,  by  all  means,  be 
preserved. 

122.  An  economical  mode  of  application  is  to 
grind  or  crush  the  seed,  scatter  it  in  deep  furrows, 
and  cover  it  up  some  time  before  planting.  The 
practice  of  scattering  the  seed  in  the  drill  ^t  the  time 
of  planting  does  very  well,  provided  too  large  a  quan- 
tity is  not  used.  The  decay  of  cotton-seed  is  a  spe- 
cies of  combustion,  or  fermentation  which  generates 
considerable  heat,  and  if  the  roots  of  the  young  cot- 
ton-plant are  in  contact  with  the  hot,  fermenting 
mass,  they  are  almost  sure  to  be  destroyed.  If,  how- 
ever, the  fermentation  takes  place  below  the  plant, 
with  a  layer  of  earth  between,  the  young  plant  will 
be  stimulated  and  nourished  by  the  escaping  vol- 


S6 


SCI  EN  TIFIC  A  GRICUL  TURE. 


atile  products  of  decomposition,  and  the  roots  thus 
strengthened  will  reach  down,  and  appropriate  the 
food  contained  in  the  decaying  seed. 

123.  To  those  living  near  an  oil-mill,  there  will 
be  great  economy  in  having  the  oil  first  extracted 
from  the  seed,  and  then  using  the  oil-cake  as  a  fertil- 
izer. The  oil  is  a  product  of  great  value  for  certain 
purposes,  but  of  little  value  as  a  manure,  because  it 
contains  only  the  organic  elements,  carbon,  hydro- 
gen, and  oxygen,  which  are  supplied  by  the  atmos- 
phere to  every  plant. 

124.  The  process  of  grinding  or  crushing  the 
seed  promotes  decomposition,  and  hastens  its  avail- 
ability as  plant-food ;  but  the  expense  of  the  neces- 
sary machinery  is  too  great  for  general  use,  unless 
the  kernel  is  to  be  used  as  food  for  stock,  for  which 
purpose  it  is  admirably  suited.  The  valuable  pro- 
ducts of  decomposing  cotton-seed  may  be  preserved 
by  composting,  or  mixing  with  other  fertilizers  which 
can  absorb  or  combine  with  its  volatile  products. 

125.  Tlje  important  object  to  be  accomplished, 
on  every  farm  or  plantation,  is  the  restoration  to  the 
soil,  in  some  form  or  other,  of  the  large  amount  of 
valuable  mineral  matter  contained  in  the  seed,  and 
the  prevention  of  its  permanent  removal  to  the  grad- 
ual exhaustion  of  the  land.  In  Europe,  rape-seed 
and  linseed-cake,  similar  to  our  cotton-seed  oil-cake, 
are  highly  esteemed  as  fertilizers. 

126.  Animal  fertilizers,  consisting  of  the  flesh  of 
all  dead  animals,  with  the  scrapings  of  tanneries  and 


THE    USE   OF  MANURES. 


57 


the  oflfal  of  slaughter-houses,  are  among  the  most 
stimulating  substances  used  to  promote  the  growth 
of  vegetation.  The  animal  structure  contains  every 
element  of  the  plant  except  silicon,  and  some  por- 
tions of  the  body  contain  most  valuable  constituents 
in  a  highly  concentrated  form.  The  products  of 
decomposition  are  especially  rich  in  nitrogen. 

127.  The  bones  and  excrements  of  animals, 
among  the  most  powerful  and  valuable  of  fertilizers, 
generally  undergo  some  manipulation,  or  preparation 
before  being  used,  which  renders  them  more  suit- 
able for  immediate  use,  or  more  convenient  for 
handling. 

128.  Raw  bones  when  dried  consist  chiefly  of 
tricalcium  phosphate  (common  phosphate  of  lime) 
and  gelatinous  matter,  in  the  proportion  of  about 
two-thirds  of  the  former  to  one-third  of  the  latter. 
Their  average  composition  may  be  stated  as  follows : 

Per  cent. 

Animal  matter 33 

Tricalcium  phosphate 57 

Calcium  carbonate 8 

Calcium  fluoride i 

Magnesium  phosphate I 

100 

129.  Bones  are  sometimes  merely  ground  to  a 
fine  powder,  and  sown  broadcast,  or  drilled  with  the 
grain  at  the  time  of  planting.  In  this  case  their  ac- 
tion is  slow,  because  they  are  insoluble  in  water,  and 


58  SCIENTIFIC  AGRICULTURE. 

their  constituents  must  be  rendered  soluble  before 
they  can  be  taken  up  by  the  plant  and  used  as  food. 
This  change  will  take  place  gradually  in  the  soil. 

130.  In  order  to  hasten  the  action  of  bones,  it  is 
customary  to  convert  them  into  what  is  known  as 
superphosphate.  This  is  done  by  mixing  the 
broken  or  ground  bones  with  about  half  their  weight 
of  common  sulphuric  acid,  or  oil  of  vitriol  diluted 
with  two  or  three  times  its  weight  of  water.  After 
the  acid  has  acted  upon  the  bones,  a  somewhat  pasty 
mass  is  formed,  which  may  be  mixed  with  ashes,  saw- 
dust, rich  earth,  refuse  of  salt-refineries,  etc.,  to  neu- 
tralize excess  of  acid. 

131.  The  insoluble  bone,  or  calcium  phosphate, 
is  thus  changed  by  the  acid  into  a  soluble  phosphate, 
commonly  known  as  superphosphate.  The  sul- 
phuric acid  removes  a  portion  of  the  calcium  from 
the  bones  forming  calcium  sulphate,  or  gypsum, 
which  is  itself  an  excellent  fertilizer.  The  addition 
of  ashes  to  neutralize  excess  of  acid  is  an  advantage 
to  the  mixture,  but  unfortunately  manufacturers  or 
dealers  sometimes  add  sand  and  earth  of  no  value, 
in  such  quantities  that  suspicion  has  been  cast  upon 
the  genuineness  of  much  of  our  commercial  super- 
phosphate. 

132.  A  large  deposit  of  tricalcium,  or  bone  phos- 
phate, the  remains  of  extinct  animals,  was  discovered 
near  Charleston,  South  Carolina,  some  years  ago.  It 
furnishes  an  abundant  supply  of  this  material,  and 
has  caused  a  reduction  in  the   cost  of  superphos- 


THE    USE   OF  MANURES. 


59 


phates.     An  analysis  of  South  Carolina  phosphate 
shows  it  to  contain  • 

Per  cent. 

Moisture 7.79 

Organic  matter  and  water  of  combination 4.60 

Silica 10.35 

Calcium  carbonate 8.20 

Tricalcium  phosphate 61.89 

Earthy  and  alkaline  salts 7.17 

Total 100.00 

133.  Hundreds  of  tons  of  cattle  and  buffalo  bones 
are  brought  from  the  Western  Plains,  and  are  either 
used  in  the  form  of  ground  bones,  or  first  converted 
into  superphosphate.  The  following  mean  of  many 
analyses  of  superphosphates,  taken  from  "  Phosphates 
of  Commerce,"  by  Jones,  will  show  their  general 
composition  : 

Per  cent. 

Moisture 1450 

Organic  and  volatile  matter 12.91 

Monocalcium  phosphate,  or  superphosphate  *. .  17.30 

Tricalcium,  or  bone  phosphate 4.16 

Calcium  sulphate 47-78 

Alkaline  salts 0.15 

Sand 3.20 

Total 100.00 

*  Equal  to  27.08  per  cent,  of  bone  phosphate  rendered  sol- 
uble. "  Monocalcium  phosphate,"  in  the  above  statement,  is 
sometimes  called  "  biphosphate  of  lime."  It  is,  according  to 
the  modern  chemical  nomenclature,  tetrahydrogen  calcium  di 
phosphate. 


6o  SCIENTIFIC  AGRICULTURE. 

134.  The  manufacture  of  superphosphates  is  per- 
haps too  difficult  for  the  ordinary  farmer,  and  yet 
in  some  cases  it  can  be  made  profitable.  To  any 
one  disposed  to  try  the  experiment,  the  following 
directions  are  given,  which,  if  strictly  followed,  will 
insure  a  good  result : 

Secure  a  carboy  of  sulphuric  acid,  commonly 
known  as  "  oil  of  vitriol,"  break  up  the  bones  as  fine 
as  possible,  and  to  one  hundred  pounds  of  bones 
add  forty  pounds  of  acid,  previously  mixed  with 
twice  its  bulk  of  water,  and  cooled.  The  mixing  of 
the  acid  and  water  together  produces  great  heat. 
It  is  best  to  pour  the  acid  into  the  water  with  con- 
stant stirring.  After  the  mass  has  become  pasty  by 
solution  of  the  bones,  add  ashes,  mix  thoroughly, 
and  allow  the  mass  to  dry.  It  can  easily  be  re- 
duced to  a  powder,  and  thus  applied  to  the  soil.  A 
long  trough  or  one  or  more  barrels  may  be  used  in 
making  the  solution,  or  the  finely  broken  bones  may 
be  placed  in  a  pile  on  a  suitable  floor,  and  sprinkled 
from  time  to  time  with  diluted  acid.  The  acid  must 
be  handled  with  care,  as  it  is  highly  corrosive.  From 
two  to  three  hundred  pounds  of  this  mixture  should 
be  used  per  acre. 

135.  Dr.  Nichols,  in  his  "barn-floor  lecture," 
gives  the  following  practical  directions  for  making 
superphosphate  from  charred  bones,  a  substance 
used  by  sugar-refiners  for  decolorizing  syrups,  and 
then  sold  to  makers  of  fertilizers : 

"  A  box  four  feet  square  and  one  foot  deep  is 


THE    USE  OF  MANURES.  6 1 

lined  with  thick  sheet-lead — the  lead  in  one  piece, 
soldered  at  the  corners  strongly  with  lead  solder. 
Its  capacity  is  just  right  for  making  one-fourth  of  a 
ton  of  superphosphate  at  a  time,  and  it  requires  a 
whole  carboy  of  vitriol,  so  that  no  fractional  parts 
of  acid  are  left  to  cause  trouble.     It  requires  : 

One  carboy  of  oil  of  vitriol 165  pounds 

Bone-charcoal 380       " 

Water 10  gallons 

"  The  water  is  first  placed  in  the  trough,  and  the 
acid  is  added  to  it  gradually,  causing  a  great  boiling, 
with  evolution  of  heat  and  steam.  It  takes  about  an 
hour  for  the  reaction  to  become  complete,  and  then 
it  will  soon  dry  atid  be  free  from  moisture.  It  needs 
no  grinding,  it  is  ready  for  the  field  as  soon  as 
cool." 

136.  Guano,  one  of  the  most  costly  and  valuable 
of  fertilizers,  was  in  use  by  the  inhabitants  of  South 
America,  when  the  Spaniards  under  Pizarro  overran 
and  subdued  the  powerful  empire  of  the  Incas.  Pres- 
cott,  in  his  history  of  **  The  Conquest  of  Peru,"  gives 
an  interesting  account  of  the  progress  made  in  agri- 
culture by  the  aborigines  of  that  country.  In  some 
places  where  the  dry  sandy  plains  were  unproduc- 
tive, they  sank  immense  pits,  some  of  whicTi  were  an 
acre  or  more  in  extent,  and  dug  out  to  a  depth  of 
fifteen  or  twenty  feet,  in  order  that  moisture  suffi- 
cient for  vegetation  might  be  afforded.  Other  con- 
ditions of  fertility  were  supplied  by  thorough  pul- 


62  SCIENTIFIC  AGRICULTURE. 

verization  of  the  soil  and  a  systematic  application  of 
fertilizers. 

137.  The  fertilizer  in  common  use  among  the  Pe- 
ruvians was  guano,  the  excrement  of  immense  flocks 
of  sea-birds  which  frequent  the  rocky  islands  near  the 
coast.  Countless  numbers  of  birds  have  for  centu- 
ries hatched  and  reared  their  young  on  these  islands, 
leaving  deposits  which  cover  a  large  extent  of  sur- 
face, and  are  in  places  from  twenty  to  fifty  feet  in 
thickness.  It  was  estimated,  thirty  years  ago,  that 
on  the  Chincha  group  of  islands  there  were  from 
twenty  to  twenty-five  millions  of  tons.  It  has  been 
so  long  accumulating  that  in  some  localities  the  de- 
posit is  found  in  layers  with  sand  like  a  regular  geo- 
logical formation. 

138.  The  importance  of  this  fertilizer  was  so 
highly  appreciated  by  the  old  Peruvians  that,  when 
the  Spaniards  first  visited  the  country,  special  laws 
were  in  operation  to  regulate  its  use,  and  enforce  its 
application  to  the  soil  by  those  engaged  in  agricul- 
ture. Its  value  was  not  known  or  appreciated  in 
Europe  or  in  our  own  country  until  within  the  last 
thirty  or  forty  years.  The  credit  of  introducing  it 
into  Europe  is  ascribed  to  Humboldt.  The  first 
cargo  was  taken  to  England  in  1826,  but  its  value 
was  not  understood  until  a  number  of  years  after- 
ward. 

139.  Liebig,  in  his  "  Letters  on  Modern  Agricul- 
ture," says:  "Before  1840,  guano  had  never  been 
used  as  a  manure  on  a  European  field.    When  the  first 


THE    USE   OF  MANURES.  63 

vessel  loaded  with  guano  arrived  at  Liverpool,  nu- 
merous experiments  were  made  with  the  new  manure 
which  proved  failures,  and  agriculturists  were  not 
agreed  about  its  utility  until  they  had  practically 
tested  its  use.  Since  that  time,  many  hundreds  of 
ships  have  passed  to  and  fro,  and  have  brought  to 
the  European  Continent  guano  to  the  value  of  about 
300,000,000  florins  (about  $125,000,000) ;  and,  within 
the  same  period,  there  has  been  produced  a  surplus 
of  more  than  400,000,000  cwt.  of  corn,  or  of  its  equiv- 
alent in  flesh.  It  is  true,  guano  would  have  found 
its  way  to  Europe  even  without  the  recommenda- 
tion of  science,  but  it  would  not  have  made  its 
way  so  speedily.  In  the  late  period  of  sterility 
through  which  we  have  passed,  it  has  been  the 
means  of  alleviating  the  wants  of  many  millions 
of  men." 

140.  The  first  shipment  of  guano  to  the  United 
States  was  made  in  1845,  and  up  to  June  30,  1855, 
about  half  a  million  tons  had  been  imported,  while 
the  amount  sent  to  Europe  during  the  same  period 
was  vastly  greater.  The  Government  of  Peru  has 
derived  a  large  revenue  from  the  sale  of  this  valuable 
fertilizer,  and  the  ships  of  all  nations  have  engaged 
so  actively  in  the  trade  that  the  supply  on  the  isl- 
ands has  greatly  diminished.  The  ocean  has  been 
searched  for  other  islands  containing  similar  de- 
posits, and,  while  some  have  been  found,  none  are 
esteemed  so  highly  as  those  on  the  coast  of  South 
America. 


64  SCIENTIFIC  AGRICULTURE. 

141.  ,0n  these  Peruvian  islands  it  seldom  or  never 
rains,  while  the  hot  sun  rapidly  evaporates  the  mois- 
ture naturally  contained  in  the  deposit,  and  leaves 
the  valuable  constituents  in  their  most  concentrated 
form.  On  other  islands  frequented  by  sea-birds,  a 
great  deal  of  that  which  is  valuable  in  the  deposits  is 
washed  out  by  rains  more  or  less  frequent.  Guano 
has  been  brought  from  a  few  islands  on  the  coast  of 
Africa  and  other  parts  of  the  world  where  rain  sel- 
dom falls,  but  none  has  been  found  equal  in  value  to 
the  Peruvian. 

142.  The  guano-producing  birds  feed  on  fish,  a 
food  especially  rich  in  phosphates  and  nitrogenous 
compounds.  The  mixture  of  their  solid  and  liquid 
excrements  contains  in  a  highly  concentrated  form 
those  very  elements  which  are  most  likely  to  be 
deficient  in  soils^  and  hence  its  universal  applica- 
bility. 

143.  The  composition  of  guano  varies  consider- 
ably in  different  samples.  An  average  analysis  of 
Peruvian  guano  imported  into  Ireland  in  1876  is 
given  by  Johnston  and  Cameron  as  follows : 

Per  cent. 

Moisture 13.13 

Organic  matter,  etc.* 48.17 

Calcium  phosphate ....  26.58 

Alkaline  salts i  i.cx) 

Insoluble  matter ~ 1.12 

100.00 

*  Yielding  ammonia . .     11.80. 


THE    USE   OF  MANURES. 


65 


144.  Peruvian  guano  contains  less  moisture  than 
African  and  Patagonian  because  the  climate  of  Peru 
is  drier.  It  also  has  a  less  pungent  smell  of  ammonia. 
As  guano  is  often  adulterated  with  sand,  earth,  etc., 
the  following  physical  properties  and  tests  will  en- 
able one  who  is  not  a  chemist  to  distinguish  between 
a  good  guano  and  one  of  inferior  quality,  or  one 
which  has  been  adulterated. 

145.  Genuine  guano  is  a  substance  of  a  yellow- 
ish-brown color,  of  a  peculiar  urinous  odor,  and 
has  mixed  with  it,  white  lumps  or  fragments.  When 
heated  on  a  shovel  or  iron  plate,  at  least  half  of  it 
will  volatilize,  and  nearly  the  whole  of  the  remain- 
der will  dissolve  in  dilute  hydrochloric  acid.  Sand 
and  earthy  adulterations  will  be  left  undissolved,  which 
in  good  guano  does  not  amount  to  more  than  from 
I  to  2  per  cent.  When  first  heated,  it  gives  off 
white  vapors  with  a  strong  smell  of  ammonia.  This 
odor  is  greatly  increased  by  the  addition  of  lime. 
The  ash  should  be  white  or  grayish ;  a  yellow  or 
red  ash  indicates  an  admixture  of  clay  or  earthy 
matter. 

146.  The  highly  stimulating  effect  of  guano  is  due 
to  the  large  amount  of  nitrogenous  matter  which 
it  contains.  The  atmosphere  furnishes  nitrogen  to 
plants  in  the  form  of  ammonia,  but  not  in  sufficient 
quantity  to  meet  the  demands  of  a  luxuriant  growth 
of  wheat,  corn,  or  other  crop.  This  must  be  sup- 
plied by  decaying  nitrogenous  matter,  salts  of  am- 
monia, or  nitrates. 


66  SCIENTIFIC  AGRICULTURE. 

147.  The  newly  sprouted  plant  stands  ready  to 
grow,  it  may  be  with  all  its  organs  perfect,  and  with 
every  article  of  food  at  hand,  but,  so  long  as  there  is . 
only  a  limited  supply  of  one  important  element,  the 
rapidity  and  vigor  of  its  growth  will  be  retarded.  The 
air  contains  an  abundant  supply  of  nitrogen,  but  not 
one  atom  of  it,  as  chemists  believe,  is  contributed 
directly  to  the  growth  of  plants.  This  important 
element,  before  it  can  be  used  as  plant-food,  must  be 
in  union  with  some  other  element,  and  guano  furnish- 
es it  in  the  best  possible  combination.  The  phos- 
phates, too,  which  exist  so  largely  in  guano  and  other 
salts,  give  additional  value  to  this  fertilizer. 

148.  Guano,  then,  as  we  have  shown,  promotes 
the  growth  of  vegetation  by  furnishing  a  large  supply 
of  nitrogen  in  an  available  form,  and  a  few  other 
highly  important  constituents  of  our  most  valuable 
crops.  As  it  does  not  contain  all  the  elements  of 
plant-food,  there  may  be  soils  which  it  will  not  great- 
ly benefit  unless  mixed  with  other  substances.  It  is 
well  to  keep  in  mind  the  fact  that  all  the  elements 
of  plants  are  necessary  for  growth.  The  reports  of 
failure  in  the  use  of  guano  and  other  fertilizers,  and 
statements  to  the  effect  that  they  "  run  out  "  and,  in 
the  end,  "  make  the  soil  poorer,"  may  be  explained 
by  the  fact  that  such  manures  lack  some  elements 
which  every  fertile  soil  must  contain  ;  or  they  may 
so  stimulate  a  comparatively  poor  soil  that  in  a  few 
years  the  supply  of  some  important  element  which 
the  giiano  or  other  manure  lacks  will  be  exhausted. 


'f'HE    USE   OF  MANURES.  67 

Of  course,  a  further  application  of  guano  without 
the  addition  of  this  deficient  element  will  prove  a 
failure.  The  fauI^is  not  in  the  fertilizer,  but  in  not 
supplying  other  material. 

149.  It  is  customary  to  mix  guano  with  other  fer- 
tilizers not  so  rich  in  ammonia,  and  thus  have  a  ma- 
nure that  can  be  used  profitably  for  almost  any  crop. 
A  large  number  of  "  manipulated  guanos  "  are  sold, 
and  where  the  manipulation,  or  mixing  with  other  fer- 
tilizers, has  been  fairly  and  honestly  done,  such  mix- 
tures are  highly  beneficial  and  economical. 

150.  Peruvian  guano  and  other  strongly  nitro- 
genous manures  should  never  be  placed  in  imme- 
diate contact  with  the  seed,  because  the  ammonia 
given  off  is  very  caustic,  and  will  kill  the  seed-germ. 
It  may  be  placed  under  the  seed  with  a  few  inches 
of  earth  between,  or  at  the  side,  the  former  being 
preferable. 

151.  A  mixture  of  one  hundred  pounds  of  Peru- 
vian guano  with  two  hundred  of  a  good  superphos- 
phate per  acre  gives  excellent  results.  The  ingre- 
dients should  be  thoroughly  mixed,  sown  broadcast, 
and  turned  in  with  the  wheat  or  other  grain,  or  they 
may  be  placed  under  the  bed  on  which  cotton  or 
corn  is  to  be  planted.  In  wheat-growing  States, 
drills  are  used  both  for  planting  the  wheat  and  for 
depositing  the  guano  and  superphosphate.  Some 
farmers  prefer  scattering  the  fertilizer  broadcast, 
whether  for  cotton,  wheat,  or  other  crop. 

152.  It  will  not  do  to  mix  guano  with  fresh  ashes 


68  SCIENTIFIC  AGRICULTURE. 

or  lime,  because  the  potash  contained  in  ashes,  as 
well  as  lime,  sets  free  the  ammonia.  This  ammonia, 
in  all  ammoniacal  fertilizers,  is  either  free  or  in  com- 
bination with  acids.  Potash,  soda,  and  lime  have 
a  stronger  affinity  for  these  acids  than  the  ammonia, 
and  hence  they  take  its  place.  The  ammonia  being 
a  gas,  passes  off  and  diffuses  itself  in  the  air.  It  is 
important  to  understand  the  chemical  principles  in- 
volved in  mixing  fertilizers,  as  well  as  in  their  action 
when  applied  to  the  soil. 

153.  Stable  or  farm-yard  manure  is  the  most 
common  of  fertilizers,  and  one  which  every  farmer 
and  planter  can  have  in  great  abundance  without 
much  trouble  or  outlay  of  money.  It  only  requires 
the  exercise  of  a  little  care  in  its  preservation  in  or- 
der to  secure  a  large  supply  on  every  farm.  Stable- 
manure  consists  of  the  solid  and  liquid  excrements 
of  animals  which  feed  on  some  of  our  most  valuable 
crops,  mixed  with  portions  of  these  crops  in  a  more 
or  less  advanced  stage  of  decomposition.  It  consti- 
tutes a  stimulating  and  nutritive  fertilizer  applicable 
to  all  crops. 

154.  The  value  of  stable-manure  depends  to  some 
extent  on  the  food  of  the  animal ;  the  richer  the  food, 
the  better  the  manure.  The  liquid  portion  is  espe- 
cially rich  in  phosphates  and  compounds  of  nitrogen, 
and  should  never  be  allowed  to  run  to  waste.  When- 
ever a  manure-heap  gives  out  a  strong  smell,  some 
of  its  valuable  constituents  are  escaping.  In  such 
cases,  the  smell  of  ammonia  may  not  be  perceptible, 


THE    USE   OF  MANURES.  69 

but  its  escape  can  easily  be  determined  by  the  com- 
mon test  for  this  substance,  that  is,  the  formation  of 
a  white  vapor  with  hydrochloric  acid.  A  glass  rod 
dipped  into  this  acid,  and  brought  in  contact  with 
the  gaseous  ammonia,  will  show  the  effect  mentioned. 
To  prevent  the  escape  of  ammonia,  the  heap  as  it 
accumulates  should  be  covered  or  mixed  with  earth, 
or  sprinkled  occasionally  with  dilute  hydrochloric, 
or  sulphuric  acid,  or  solution  of  ferrous  sulphate, 
known  as  copperas.  Lime  and  ashes  must  not  be 
added,  because  they  would  release  the  ammonia,  in- 
stead of  retaining  it. 

155.  Manure-heaps  should  be  kept  moist  in  order 
that  fermentation  or  decomposition  may  go  on,  but 
should  not  be  exposed  to  violent  rains  which  wash 
out  soluble  ingredients  of  great  value.  Perhaps  the 
best  and  most  economical  plan  for  general  use,  is  to 
pile  the  manure  carefully  in  rail  pens  and  cover 
lightly  with  boards,  and,  even  if  not  covered,  the 
pens  will  prevent  the  scattering  and  wasting  of  the 
manure.  The  excrements  of  all  our  domestic  ani- 
mals should  be  added  to  these  piles,  together  with 
the  sweepings  of  yards,  and  refuse  of  all  kinds.  By 
this  means,  with  a  little  attention  and  no  outlay  of 
money,  much  valuable  material  which  is  now  lost 
eould  be  restored  to  the  soil. 

156.  Human  excrements,  so  abundant  in  large 
cities,  form  a  manure  of  considerable  value.  When 
dried,  powdered,  and  mixed  with  charcoal,  gypsum, 
etc.,  it  is  sold  under  the  name  of  poudrette.     Large 


70 


SCIENTIFIC  AGRICULTURE. 


quantities  are  prepared  in  Europe  which  command 
a  good  price,  but  in  this  country  it  is  used  to  a 
very  limited  extent.  The  efforts  thus  far  made 
to  utilize  the  sewage  of  cities  have  in  some  in- 
stances proved  successful,  but  there  are  difficulties 
yet  to  be  removed  before  its  profitable  use  can 
become  general. 

157.  Animal  manures  are  richer  than  vegetable 
because  they  contain  more  nitrogen,  which  in  the 
process  of  fermentation  and  decay  unites  with  hy- 
drogen to  form  ammonia,  and  because  they  also  con- 
tain a  larger  proportion  of  valuable  inorganic  ele- 
ments. The  effect  of  respiration  and  digestion,  the 
two  great  vital  functions  of  the  animal  system,  is  to 
extract  carbon  and  hydrogen  from  the  food  through 
the  blood  and  lungs  where  they  escape  as  carbon 
dioxide  and  water.  The  water  in  large  quantities 
passes  through  the  pores  of  the  skin,  leaving  the 
other  constituents  in  a  more  concentrated  form. 


CHAPTER  VIII. 

MINERAL    FERTILIZERS. 


158.  The  list  of  mineral  fertilizers  embraces 
a  large  number  of  substances,  only  a  few  of  which, 
however,  will  be  mentioned,  such  as  lime,  marl,  gyp- 
sum, salt,  and  ashes. 


MINERAL  FERTILIZERS. 


71 


159.  Lime,  or  calcium  oxide,  is  made  by  heating 
common  limestone  in  a  suitable  kiln.  This  mineral, 
when  pure,  consists  of  lime  in  combination  with  car- 
bon dioxide,  or  carbonic-acid  gas.  The  rock  is  bro- 
ken into  small-sized  pieces,  placed  loosely  in  what 
is  known  as  a  kiln,  and,  by  means  of  wood  or  coal, 
thoroughly  heated  until  the  carbon  dioxide  is  driven 
off.  Calcium  oxide,  or  quicklime,  is  left.  One  hun- 
dred pounds  of  pure  limestone  yield  fifty-six  pounds 
of  lime. 

160.  If  water  be  poured  on  quicklime,  a  portion 
of  the  water  will  combine  with  it,  giving  out  heat, 
and  forming  slaked  lime.  The  same  result  will  be 
produced  by  exposing  the  quicklime  to  moist  air. 
Long  exposure  to  air  will  result  in  a  reunion  of  car- 
bon dioxide  with  the  lime.  The  new  carbonate 
will  be  in  a  finely  divided  condition,  which  is  better 
for  fertilizing  purposes  than  the  original  limestone, 
though  not  so  good  as  the  slaked  lime  (30). 

161.  One  hundred  pounds  of  quicklime  (also 
called  caustic  lime)  unite  with  thirty-two  pounds  of 
water  in  the  process  of  slaking.  This  water  is  not 
mixed  with  the  lime,  but  forms  a  chemical  compound 
known  as  calcium  hydroxide.  This  hydroxide  is 
slighty  soluble  in  water,  of  caustic  taste,  and  when 
mixed  with  sand  forms  common  mortar.  The  hard- 
ening of  mortar  is  due  to  the  absorption  of  carbon 
dioxide  from  the  air,  and  a  gradual  union  of  the  lime 
with  the  silica,  or  sand. 

162.  The  application  of  lime  to  soils  furnishes  at 


7a 


SCIENTIFIC  AGRICULTURE. 


least  one  mineral  constituent  to  plants,  one,  however, 
that  generally  exists  in  soils,  and  hence  its  valuable 
and  often  surprising  effects  are  not  to  be  attributed 
to  the  plant-food  it  contains  so  much  as  to  other  im- 
portant purposes  which  it  serves.  Its  alkaline  prop- 
erties cause  it  to  neutralize  acids,  which  sometimes 
exist  injuriously  in  soils.  It  also  renders  stiff  clays 
light  and  mellow,  and  aids  in  the  decomposition  of 
organic  substances,  and  of  some  insoluble  inorganic 
compounds.  In  other  words,  lime  corrects  "  sour- 
ness "  in  lands,  destroys  excess  of  vegetable  matter, 
lightens  heavy  clay  soils,  and  releases  potash  for  the 
use  of  plants  by  decomposing  silicates. 

163.  Marl  is  a  mixture  of  calcium  carbonate — 
derived  chiefly  from  the  shells  of  animals — clay  and 
sand  in  variable  proportions.  It  is  generally  valued 
according  to  the  amount  of  calcium  carbonate  it  con- 
tains, which  may  vary  from  five  to  ninety  per  cent., 
though  in  almost  all  marls  there  are  other  valuable 
constituents.  The  calcium  carbonate,  or  carbonate 
of  lime,  as  it  is  generally  called,  is  usually  in  a  finely 
divided  state,  and  can  be  readily  used  as  food  by  the 
plant. 

164.  The  celebrated  New  Jersey  green-sand  marl 
contains  a  large  percentage  of  potash,  which  gives  it 
great  value.  Excellent  marls  are  found  in  many 
parts  of  the  country,  and  need  no  preparation  before 
using.  The  following  analysis  by  Professor  Norton 
will  give  some  idea  of  the  composition  of  an  excel- 
lent marl  • 


MINERAL  FERTILIZERS.  73 

Per  cent. 

Calcium  oxide  (lime) 35-00 

Carbon  dioxide 45 -02 

Oxide  of  iron  and  aluminium,  )  , 

'  '- 2.69 

with  traces  of  phosphoric  acid  S 

Magnesium  oxide 0.66 

Organic  matter 7.06 

Sand 9.57 

lOO.CX) 

165.  Some  marls  consist  almost  entirely  of  shells 
more  or  less  broken  ;  in  others,  clay  or  sand  predom- 
inates. Good  marl  always  gives  off  a  large  quantity 
of  carbon  dioxide  on  the  addition  of  a  strong  acid, 
and  in  this  way  some  estimate  may  be  formed  of  its 
value  (31).  This  fertilizer  is  particularly  well  suited 
for  application  to  sandy  lands,  supplying  the  very 
elements  which  such  lands  generally  need  for  the 
continued  production  of  good  wheat  and  cotton 
crops. 

166.  Gypsum,  or  calcium  sulphate,  also  called  land 
plaster,  is  a  very  important  mineral  fertilizer  and  has 
long  been  in  use  as  a  valuble  manure  for  corn,  tobacco, 
wheat,  clover,  and  the  grasses  generally.  It  is  com- 
posed of  lime  and  an  oxide  of  sulphur  in  chemical 
combination  with  a  large  percentage  of  water.  This 
water  can  be  driven  off  by  heat  leaving  a  white  sub- 
stance which,  ground  to  powder,  forms  what  is 
known  as  plaster  of  Paris.  In  this  form,  it  has  the 
property  of  recombining  chemically  with  water  and 
forming  a  substance  of  the  same  composition  as  the 


74  SCIENTIFIC  AGRICULTURE. 

original  gypsum.  This  property  fits  it  admirably 
for  taking  casts  of  statuary,  for  forming  the  "  hard 
finish  "  on  the  plastered  walls  of  our  houses,  and  for 
stucco-work  of  all  kinds.  Dentists  use  it  in  large 
quantities  for  taking  casts  of  the  mouth,  and  for 
other  purposes  in  their  work,  while  it  is  useful  to 
artists  in  forming  models  from  which  to  copy  and 
perfect  the  creations  of  their  genius  (32). 

167.  Gypsum  is  found  in  nature  as  a  mineral, 
generally  as  a  white  compact  mass,  though  sometimes 
in  a  transparent  crystalline  condition,  as  in  the  min- 
eral selenite.  Alabaster  is  also  a  form  in  which  this 
mineral  is  found,  and  used  in  the  manufacture  of 
vases  and  other  ornamental  work.  The  rock  is  quite 
soft,  easily  scratched  with  a  knife,  and  whitens  on 
being  heated.  It  contains  about  twenty-one  per 
cent,  of  water.  As  a  fertilizer,  it  furnishes  lime  and 
sulphur  to  plants,  and  is  thought  to  have  the  power 
of  absorbing  ammonia  from  the  air  and  supplying  it 
to  the  plant.  To  this  important  property  Liebig 
ascribes  much  of  its  wonderful  effect  upon  young 
grass  and  wheat.  It  is  usual  to  sow  it  broadcast 
over  wheat  and  grass  during  the  early  spring,  and  to 
drop  it  with  corn  at  the  time  of  planting,  or  to  drop 
a  small  portion  on  each  hill  of  corn  after  the  corn 
has  been  thinned.  Corn  moistened  with  water  and 
rolled  in  plaster  at  the  time  of  planting,  will  get 
a  more  vigorous  start,  and  be  the  better  enabled 
to  stand  an  early  drought.  Cotton-seed  may  also 
be  very  advantageously  rolled   in  plaster  previous 


MINERAL  FERTILIZERS. 


75 


to  planting.  For  this  purpose,  the  seed  is  placed 
in  a  tub  of  convenient  size,  thoroughly  moistened 
with  water,  the  plaster  added,  and  the  whole  well 
stirred.  As  much  as  will  adhere  is  dropped  with 
the  seed. 

1 68.  Gypsum,  or  plaster,  has  no  caustic  proper- 
ties like  quicklime  and  guano,  and  therefore  seeds 
are  not  injured  by  being  placed  in  immediate  contact 
with  it.  The  vigorous,  healthy  start  which  it  gives 
to  the  young  plant  is  very  desirable  for  both  corn 
and  cotton,  since  weak,  sickly  plants  are  almost  sure 
to  suffer  from  insects,  or  perish  from  other  causes. 
The  noted  English  farmers,  Lawes  and  Gilbert,  found, 
during  four  years,  an  average  increase  of  nearly  one 
ton  of  hay  per  acre  by  the  use  of  gypsum  as  compared 
with  adjoining  land  without  gypsum.  This  is  one  of 
the  cheapest  of  fertilizers,  and  should  be  used  by  farm- 
ers and  planters  who  desire  an  increase  of  production 
by  a  moderate  outlay  of  money.  It  is  not  necessary 
to  mix  gypsum  with  superphosphate,  because,  in  the 
process  of  making  superphosphate  from  bones,  cal- 
cium sulphate,  or  gypsum,  is  always  formed  at  the 
same  time,  and  constitutes  a  large  part  of  the  super- 
phosphate. 

169.  Common  salt  has  been  used  as  a  manure 
from  very  ancient  times.  It  can  be  used  with  ad- 
vantage only  in  small  quantities,  as  a  heavy  applica- 
tion destroys  vegetation.  Common  salt,  or  sodium 
chloride,  consists  of  two  elements,  chlorine  and  so- 
dium, and  is  a  valuable  addition  to  compost-heaps. 


^6  SCIENTIFIC  AGRICULTURE. 

Its  value  as  a  manure  is  denied  by  some  experiment- 
ers. It  acts,  no  doubt,  in  an  indirect  manner,  releas- 
ing nitrogen  from  some  of  its  compounds  and  aiding 
in  the  solution  of  calcium  phosphate  and  other  salts. 
According  to  some  writers,  salt  may  be  used  to  ad- 
vantage for  checking  growth  on  lands  which  pro- 
duce such  an  excess  of  straw  as  to  cause  wheat  to 
fall  before  the  seed  is  matured. 

170.  In  chemical  language,  salts  are  compounds 
in  which  the  hydrogen  of  an  acid  is  replaced  by  a 
metal.  The  union  of  a  non-metallic  element  with  a 
metal  forms  a  salt  like  sodium  chloride.  Another 
class  of  salts  have  oxygen  in  them  in  addition  to  the 
other  non-metallic  element,  like  potassium  nitrate  or 
nitre,  sodium  nitrate  or  Chili  saltpetre.  These  are 
used  as  fertilizers,  as  are  also  sulphates  of  various 
kinds,  and  the  refuse  salts  from  salt-works  and 
chemical  manufactories.  The  utilization  of  what 
were  formerly  waste  products  is  carried  to  such 
an  extent  in  Europe  that  scarcely  anything  is  lost. 
Every  product  has  a  marketable  value,  and  what 
cannot  be  consumed  by  animals,  or  put  to  some 
useful  purpose,  is  returned  to  the  soil  as  food  for 
plants. 

171.  Among  mineral  fertilizers  may  be  classed 
the  ash  of  vegetable  substances  whether  of  wood, 
coal,  or  plants.  The  following  result  of  the  analysis 
of  the  ash  of  oak  and  beech  wood  shows  the  nature 
of  this  fertilizer : 


MINERAL  FERTILIZERS.  77 

Percentage  of  Oak.  Beech. 

Potassium  oxide 8.43  15.83 

Sodium  oxide 5.64  2.79 

Sodium  chloride 0.02  0.23 

Calcium  oxide,  or  lime 7463  62.37 

Calcium  sulphate 1.98  2.31 

Magnesium  oxide,  or  magnesia 4.49  11.29 

Iron  oxide,  or  ferric  oxide 0.57  0.79 

Phosphoric  pentoxideorphosphoric  acid.  3.46  3.07 

Silica 0.78  1.32 

100.00     100.00 

172.  The  ash  contains  all  the  mineral  matter 
which  the  plant  derives  from  the  soil,  and  is  in  a 
good  condition  to  be  used  again  as  plant-food.  The 
potassium  and  sodium  salts  are  easily  washed  out 
by  rains,  being  very  soluble  in  water.  In  the  pro- 
cess of  making  soap,  ashes  are  leached  for  the  pur- 
pose of  obtaining  these  two  alkaline  metals.  Other 
substances,  however,  remain,  so  that  even  leached 
ashes  are  valuable  as  a  manure. 

173.  A  compost  is  simply  a  mixture  of  differ- 
ent fertilizing  materials.  They  are  generally  heaped 
together  and  allowed  to  ferment,  or  decompose. 
Organic  matter,  such  as  straw,  chips,  cotton-seed, 
dead  animals,  refuse  from  slaughter-houses,  etc, 
must  undergo  decay  or  putrefaction  before  they  be- 
come valuable  as  manure,  and  in  doing  so  they  give 
off  ammonia  which  will  be  lost  unless  they  be  mixed 
with  earthy  or  other  inorganic  matter  to  absorb  the 
gas  as  fast  as  formed.     Composting  is  the  art  of  so 


78  SCIENTIFIC  AGRICULTURE 

mixing  these  that  a  valuable  fertilizer  will  be  formed, 
and  no  important  constituents  escape.  Such  mix- 
tures of  raw  material  must  be  kept  moist,  but  must 
not  be  exposed  to  rains  that  will  dissolve  out  soluble 
salts.  On  every  farm  or  plantation  properly  man- 
aged, all  such  substances  will  be  preserved  and  re- 
turned to  the  soil. 

174.  Pendleton,  in  his  valuable  work  on  "Scien- 
tific Agriculture,"  gives  good  directions  for  such  a 
compost-heap,  as  follows :  "  A  layer  of  stable-ma- 
nure six  inches  thick,  with  a  good  sprinkling  of 
ground  phosphate  over  it ;  then  a  layer  of  cotton- 
seed three  inches  thick  (previously  saturated  with 
water),  and  then  another  sprinkling  of  superphos- 
phate, say  half  an  inch  thick ;  then  a  layer  of  stable- 
manure,  and  so  on  until  the  heap  is  completed, 
which  should  be  conical  in  form.  Over  the  whole 
heap,  when  sufficiently  large,  apply  several  inches  of 
dry  clay  soil,  if  you  choose,  which  will  absorb  every 
particle  of  the  escaping  ammonia.  If,  however,  this 
crust  should  become  so  saturated  as  to  allow  it  to 
escape,  an  additional  coating  of  soil  can  be  ap- 
plied." 

175.  If  the  cotton-seed  and  superphosphate  are 
not  on  hand,  use,  with  the  stable-manure,  the  sweep- 
ings of  the  yard,  old  mortar,  leached  ashes,  bones, 
scrapings  from  poultry-houses  and  yards,  swamp 
muck,  the  earth  from  old  ponds,  and  any  and  every* 
kind  of  waste  matter  that  is  usually  thrown  away  or 
hauled  off  that,  it  may  not  become  offensive.     Such 


ROTATION  OF  CROPS. 


79 


piles  should  be  covered  with  a  thin  layer  of  earth,  to 
be  added  to  whenever  bad-smelling  gases  are  found 
to  escape. 

176.  Professor  Ville,  a  noted  French  writer  on 
fertilizers,  calls  a  "  complete  manure"  one  that  con- 
tains nitrogen,  potassium,  phosphorus,  and  lime,  in 
suitable  proportions  to  meet  the  demands  of  a  given 
crop.  These  four  elements  are  the  only  ones  likely 
to  be  deficient ;  and  he  advises  farmers  to  purchase 
the  chemical  salts  containing  these  elements,  and  mix 
them  according  to  formulae  given  in  his  work  on 
"Chemical  Manures."  A  good  superphosphate  with 
nitre,  or  with  some  salt  of  ammonia,  and  one  of  po- 
tassium, would  constitute  such  a  mixture. 


CHAPTER   IX. 

ROTATION    OF    CROPS. 

177.  The  fact  has  long  been  known  that  it  is  not 
best  to  grow  the  same  kind  of  crop  on  the  same 
land  for  a  number  of  years  in  succession.  I'hus, 
the  yield  of  corn,  wheat,  oats,  tobacco,  or  other  crop, 
if  grown  on  the  same  land  without  change  will  grad- 
ually diminish,  while  if  these  crops  be  made  to  alter- 
nate, that  is,  first  one  and  then  another,  the  aggre- 
gate product  will  be  much  greater.  This  change  is 
called  rotation  of  crops. 

178.  The  advantages  of  rotation,  or  change  of 


8o  SCIENTIFIC  AGRICULTURE. 

crops,  result  from  the  following  considerations  :  In 
the  first  place,  different  crops  require  elements  in 
different  proportions  ;  one  requires  more  potash  than 
another,  or  lime,  or  phosphoric  acid,  or  nitrogen,  or 
some  other  constituent.  By  reference  to  the  table 
in  paragraph  54,  it  will  be  seen  that  potatoes  require 
more  potash  than  wheat  or  corn,  while  these  require 
more  phosphoric  acid ;  clover  and  tobacco  need  a 
great  deal  of  lime,  and  so  with  other  crops.  A  num- 
ber of  crops  of  potatoes  in  succession,  without  the 
addition  of  potash  in  some  form,  will  use  up  the 
available  supply,  unless  the  quantity  be  very  large. 
Before  this  comes  to  pass,  another  crop  that  re- 
quires less  of  potash  but  more  of  some  other  ele- 
ment might  grow  well,  while  the  potatoes  would  not 
flourish. 

179.  In  the  second  place,  rotation  of  crops  gives 
time  for  the  disintegrating  action  of  the  atmosphere, 
rain,  and  frost  to  prepare  new  material  from  the 
rock-particles  in  the  soil,  and  get  it  in  a  form  to  be 
used  by  the  plant.  One  crop  may  use  up  the  avail- 
able food  of  a  particular  kind  faster  than  it  can  be 
prepared  by  these  natural  agencies. 

180.  In  the  third  place,  rotation,  or  change  of 
crop,  when  properly  managed,  enables  one  plant  to 
prepare  food  for  another.  Thus  clover  sends  a  long 
tap-root  deep  down  into  the  soil,  and  brings  up  food 
to  the  surface.  When  the  roots  decay,  the  wheat- 
plant  that  has  surface-roots  mainly  can  use  the  food 
prepared  by  the  clover. 


ROTATION  OF  CROPS.  8i 

i8i.  In  the  fourth  place,  different  .crops  require 
different  modes  of  cultivation,  so  that  the  physical 
properties  of  the  soil  are  improved  by  rotation. 
Grass-lands  in  a  few  years  become  hard  and  require 
to  be  loosened  up,  which  can  be  done  by  the  culti- 
vation of  a  crop  of  corn,  followed  by  one  of  wheat, 
and  the  re-sowing  of  grass. 

182.  Not  only  is  a  change  of  crops  desirable,  but 
an  occasional  change  of  seed  is  found  to  be  of  great 
benefit.  Wheat  grown  on  stiff  clay-lands  for  some 
years  will  be  improved  by  getting  seed  from  that 
grown  on  sandy  soil,  and  that  on  sandy  soil  by  ob- 
taining seed  from  wheat  grown  on  stiff  clay.  An 
occasional  change  of  seed  from  one  latitude  to  an- 
other is  alo  found  to  be  beneficial. 

183.  Crops  that  require  the  same  elements  in 
about  the  same  proportions  should  not  follow  each 
other,  nor  those  that  are  similar  in  their  mode  of 
growth.  Wheat  and  corn  which  depend  mainly  on 
surface-roots  will  do  well  after  clover,  cotton,  or  to- 
bacco, which  have  long  tap-roots  that  extend  down 
into  the  subsoil.  The  greater  the  difference  in  the 
constitution  and  character  of  two  crops,  the  more 
likely  are  they  suited  to  follow  each  other.  Climate 
and  soil  have  much  to  do  in  determining  the  best 
rotation. 

184.  A  good  rotation  for  three  years  is — 


First  year 

Com 

Second  " 

Wheat 

Third    " 

Clover 

g^  SCIENTIFIC  AGRICULTURE. 

A  good  four  years'  rotation  is  to  allow  the  clover 
to  remain  two  years.  In  England,  where  corn  is 
not  raised,  a  popular  four  years'  rotation  is — 

First  year  Turnips  or  other  root-crop 

Second "  Barley 

Third    "  Clover 

Fourth "  Wheat 

A  six  years'  rotation  : 

Clover  Com 

Wheat,  two  years        Wheat 
Clover 

185.  For  the  tobacco-planter,  a  good  rotation  is — 

First  and  second  year  Clover 
Third  year  Tobacco 

Fourth   "  Wheat 

This  will  keep  the  land  fertile,  or  even  improve 
it.    For  the  cotton-planter — 


First  year 

Clover  or  peas 

Second  " 

Cotton 

Thii-d    " 

Wheat 

In  much  of  the  cotton-growing  region  in  the 
South,  cotton  is  grown  year  after  year  without 
change,  to  the  great  detriment  of  the  land,  except, 
perhaps,  in  river-bottoms,  where  the  soil  is  im- 
mensely rich  and  very  deep. 

186.  It  is  best  in  the  above  rotations  not  to  re- 
move the  crop  of  clover,  but  let  it  lie  on  the  ground, 
and  be  turned  under  at  the  proper  time.  In  fact, 
there  is  no  better  way  to  improve  land  than  by  plow- 


ROTATION  OF  CROPS. 


83 


ing  in  the  clover-crop  after  it  has  fallen  on  the 
ground,  and  undergone  partial  decay.  The  long  tap- 
roots of  this  plant,  as  heretofore  mentioned,  go  down 
very  deep,  and  work  up  a  great  deal  of  material  as 
food,  and  when  the  plant  decays  it  furnishes  all  its 
elements  to  wheat,  corn,  or  other  crop  that  may  fol- 
low. Old  farmers  know  that,  if  land  will  only  pro- 
duce clover,  it  can  be  improved. 

187.  It  was  once  thought  that  the  advantages  of 
rotation  are  due  in  some  measure  to  the  excretion, 
or  giving  out,  of  material  by  the  roots  of  one  plant 
which  serves  as  food  to  another.  It  is  not  believed 
now  that  plants  have  the  power  to  excrete,  or  give 
out,  any  such  material.  Plants  do  have  some  power 
of  selection  in  taking  in  their  food,  for  we  know 
that,  when  different  plants  are  grown  in  the  same 
soil,  they  contain  different  proportions  of  the  same 
elements,  but  there  is  no  proof  that  they  all  take  in 
the  same  substances  and  give  out  from  their  roots 
what  each  does  not  need  for  growth. 

188.  No  kind  of  rotation  will  secure  good  crops 
if  any  one  or  more  of  the  elements  which  a  crop 
needs  be  entirely  absent  from  the  soil,  or  if  the  food 
is  in  such  a  condition  that  plants  can  not  appropri- 
ate it.  In  such  cases,  fertilizing,  or  manuring,  is  the 
only  way  to  restore  such  a  soil  or  make  it  fertile.  It 
is  true  that  wheat  may  be  grown  for  many  years  in  suc- 
cession on  some  qualities  of  land  without  manure,  but 
experience  shows  that  the  crop  gradually  diminishes 
The  exhaustion  may  be  slow,  but  it  will  surely  come 


84  SCIENTIFIC  AGRICULTURE. 

CHAPTER   X. 

THE   SELECTION    AND   CARE   OF    LIVE-STOCK, 

189.  Every  fanner  and  planter  finds  it  absolutely 
necessary  to  keep  some  kind  of  live-stock  on  his 
farm  or  plantation.  Such  work  as  plowing  and  haul- 
ing requires  horses,  mules,  or  oxen,  while  a  variety 
of  products  raised  on  every  farm  can  only  be  made 
profitable  by  being  fed  to  cattle,  sheep,  and  hogs, 
and  thus  turned  into  beef,  mutton,  pork,  and  bacon. 
The  proper  selection  and  management  of  such  stock 
become  matters  of  great  importance.  Attention  will 
be  called  to  a  few  guiding  principles. 

190.  The  kind  of  stock  to  be  kept,  above  what 
is  necessary  for  the  absolute  wants  of  the  farm  in  the 
way  of  performing  work,  and  furnishing  food,  will  in 
each  case  depend  upon  the  system  of  farming  adopted 
as  best  suited  to  the  nature  and  size  of  the  farm.  In 
selecting  stock,  whether  sheep,  cattle,  horses,  or  hogs, 
the  same  common-sense  principles  should  govern  as 
in  other  things.  The  best  breeds,  that  is,  those 
best  suited  for  particular  purposes,  should  be  se- 
lected, as  they  are  in  general  the  most  economical. 
If  the  farmer  wishes  to  raise  beef,  or  mutton,  or  pork, 
for  the  market,  he  should  select  those  breeds  that 
can  make  the  most  flesh  out  of  a  given  amount  of 
food.  Meat-producing  animals  are  machines  for 
converting  vegetable  food  into  flesh,  and  those  breeds 
that  give  the  greatest  yield  with  the  least  care  and 


SELECTION  AND  CARE  OF  LIVE-STOCK. 


85 


expense  of  management  are  the  best.  If  the  produc- 
tion of  milk,  or  of  wool,  be  the  object  in  view,  the 
same  principle  should  govern. 

191.  In  the  management  of  live-stock  of  every 
sort,  kind  treatment  is  absolutely  necessary  to 
success.  A  poor,  half-starved,  ill-used  horse  or  cow 
returns  no  profit  to  its  owner,  and  is  a  disgrace  to  the 
farmer.  The  feeding  should  be  regular  and  uni- 
form, and  proper  shelter  from  rain  and  cold  should 
be  provided.  Exposure  retards  the  full,  healthy  de- 
velopment of  young  animals,  and  prevents  the  con- 
version of  the  food  of  older  ones  into  salable  prod- 
ucts. As  in  the  human  system,  so  in  the  bodies  of 
lower  animals,  the  digestive  process,  to  be  success- 
fully carried  on,  requires  good  food,  pure  air,  and 
comfortable  surroundings. 

192.  Plants  derive  their  food  from  the  soil  and 
work  up  the  earthy,  or  inorganic,  material  into  organic 
products,  such  as  sugar,  starch,  gum,  oil,  woody  fibre, 
gluten ;  farm-animals  derive  their  food  from  these 
organic  products,  and  form  therefrom  fat,  muscle, 
blood,  and  bones.  The  plant  changes  earthy  mat- 
ter, carbon  dioxide,  and  ammonia,  into  organized 
products  in  which  is  stored  up  a  great  deal  of  force 
or  energy ;  animals  consume  these  organized  prod- 
ucts, which,  in  becoming  disorganized  in  the  body, 
give  out  force  or  energy  to  the  animal  in  the  form  of 
heat  and  animal  power.  Plants  store  up  energy 
to  be  used  by  animals. 

193.  The  body  of  an  animal  is  much  more  com- 


86  SCIENTIFIC  AGRICULTURE. 

plicated  in  its  structure  than  that  of  a  plant.  In  the 
higher  animals  it  consists  of  a  bony  skeleton,  covered 
with  flesh,  through  which  runs  a  network  of  nerves 
and  blood-vessels.  Within  a  portion  of  this  skeleton 
are  placed  the  lungs  and  digestive  organs.  Solid 
and  liquid  food  passes  through  the  mouth  into  the 
organs  of  digestion,  where  the  portion  suitable  for 
conversion  into  flesh  is  made  soluble  by  means  of 
proper  secretions.  This  nutritive  portion  is  absorbed 
by  suitable  organs,  carried  into  the  blood,  and  then 
distributed  to  all  parts  of  the  body,  where  it  be- 
comes flesh  and  bone  by  a  mysterious  process  which 
has  never  been  explained.  The  operation  is  so  deli- 
cate and  complicated,  and  so  many  organs  or  parts 
are  necessary  to  have  it  carried  on  successfully,  that 
it  is  no  wonder  animals  cannot  thrive  when  badly 
treated. 

194.  It  is  well  known  that  oxygen  of  the  air  is 
as  necessary  for  animal  life  as  for  the  burning  of 
wood  and  coal  in  our  fireplaces,  and  that  air  com- 
ing from  the  lungs  in  breathing  is  charged  with  car- 
bon dioxide.  This  can  easily  be  shown  by  breathing 
through  clear  lime-water  by  means  of  a  glass  or  oth- 
er tube.  The  water  becomes  milky,  a  result  caused 
by  the  carbon  dioxide  from  the  lungs  combining 
with  the  lime  in  solution  to  form  insoluble  calcium 
carbonate.  Just  as  the  chemical  action,  or  burning 
of  fuel  in  a  fireplace  or  under  a  steam-boiler,  pro- 
duces heat  and  force,  or  energy,  enough  to  move 
machinery,  so  the  chemical  action  within  the  body 


SELECTION  AND  CARE  VF  LIVE-STOCK. 


87 


produces  animal  heat  and  muscular  energy.  In  fact, 
no  force,  or  energy,  can  be  exerted  by  an  animal 
without  the  destruction  or  consumption  of  material, 
and  the  heat  of  the  body,  like  the  heat  of  a  fire,  can 
not  be  maintained  without  the  burning  of  fuel  of 
some  kind. 

195.  In  cold  weather,  therefore,  animals  require 
more  substantial  food  than  in  warm  weather,  in  order 
to  keep  up  a  proper  temperature  of  the  body.  Work- 
animals  also  require  more  food  than  those  that  do  no 
work,  in  order  to  supply  the  necessary  force,  or  en- 
ergy. A  certain  amount  of  food  is  required  to  keep 
up  the  ordinary  heat,  and  sustain  the  daily  "  wear 
and  tear  "  of  the  body  ;  if  the  animal  is  expected  to 
grow  or  become  fat,  an  additional  supply  is  neces- 
sary. All  farmers  know  that  hogs  fatten  faster,  oth- 
er things  being  equal,  when  kept  in  close  pens,  and 
not  allowed  to  run  at  large.  The  physical  exercise 
consumes  much  of  the  food  that  would  otherwise  go 
to  form  fat.  On  the  same  principle,  the  stall-feeding 
of  cattle  is  economical. 

196.  Some  years  ago,  Liebig,  a  noted  German 
chemist,  divided  the  food  of  animals  into  two  kinds, 
heat-forming  and  flesh-forming.  The  first  con- 
tains no  nitrogen,  like  sugar,  starch,  and  fat;  the 
second  contains  nitrogen,  like  gluten  and  albumen. 
Liebig  taught  that  the  first  kind  is  used  altogether 
for  keeping  up  the  animal  heat  and  forming  fat, 
while  the  second  supplies  force,  and  forms  flesh,  or 
muscle.     It  is  now  believed  that  this  theory  is  pot 


8S  SCIENTIFIC  AGRICULTURE. 

Strictly  true,  as  both  kinds  of  food  produce  heat  and 
energy.  It  is  true  that  an  animal  cannot  live  on 
food  that  contains  no  nitrogen.  A  dog,  or  horse, 
or  other  animal,  will  starve  if  fed  on  starch  alone. 
There  must  be  a  proper  mixture  of  both  nitrogenous 
and  non-nitrogenous  food,  to  build  up  and  sustain 
the  body. 

197.  Young  animals,  in  whose  bodies  a  rapid  for- 
mation of  muscle  is  going  on,  require  a  great  deal  of 
nitrogenous  food,  and  all  animals  require  more  non- 
nitrogenous,  or  carbonaceous  food,  in  cold  weath- 
er than  when  the  weather  is  warm.  In  ver)'  cold 
countries,  and  during  the  winter  in  temperate  cli- 
mates, men  will  eat  more  fat  meat  than  in  summer. 
The  Esquimaux,  a  people  that  live  in  the  intensely 
cold  regions  of  the  frigid  zone,  drink  oil  and  melted 
fat,  which  are  consumed  in  their  bodies  like  fuel  in 
a  stove  or  fireplace,  and  supply  heat  for  the  body. 

198.  Fat  in  animals,  like  starch,  sugar,  and  oil 
in  plants,  contains  no  nitrogen,  and,  when  an  animal 
is  not  fed,  this  fat  wastes  away  first — in  other  words, 
is  consumed.  If  the  animal  be  exposed  to  great  cold 
without  extra  food  it  cannot  fatten.  The  reason, 
therefore,  that  animals  protected  from  the  cold  of 
winter  fatten  much  faster  than  when  exposed,  is,  that 
what  would  accumulate  as  fat  is  used  in  keeping  the 
animal  warm. 

199.  The  earthy,  or  inorganic  matter,  in  plants  is 
as  necessary  for  animal  growth  as  the  organic  mat- 
ter.    The  bony  skeleton  consists  chiefly  of  calcium 


SELECTION  AND  CARE  OF  LIVE-STOCK. 


89 


phosphate,  with  a  little  calcium  carbonate  and  oth- 
er mineral  substances  derived  from  plants.  While 
plants  contain  everything  necessary  for  animal 
growth,  some  portions  are  richer  in  salts  and  nitrog- 
enous material,  and  are  therefore  considered  to  be 
of  more  value,  as  the  grain  of  wheat,  corn,  and  oats. 
Foods  differ  greatly  in  value,  as  every  farmer  knows. 
Many  experiments  have  been  made  to  determine  the 
feeding  power  of  various  kinds  of  food,  and  elabo- 
rate tables  have  been  drawn  up  to  express  their  com- 
parative value.  Every  farmer  practically  constructs 
such  a  table  for  himself,  at  least,  he  sets  a  different 
value  on  different  substances,  and  buys  and  sells 
accordingly. 

200.  In  the  following  table,  common  hay  is  taken 
as  the  standard,  and  the  numbers  opposite  each  sub- 
stance show  how  many  pounds  of  each  contain 
nourishment  equivalent  to  ten  pounds  of  hay : 

lbs.  lbs. 


Common  hay . , .  . .  10 

Clover  hay 8  to  10 

Green  clover 45  to  50 


Turnips 50 

Cabbage 20  to  30 

Peas  and  beans  ...     3  to    5 


Wheat-straw 40  to  50  I  Wheat 5  to  6 

Oat-straw 20  to  40  Oats 4  to  7 

Pea-straw 10  to  15  Com 5 

Potatoes 20  I  Oil-cake  (linseed)..  2  to  4 

Of  course,  such  tables  represent  only  general 
results.  Much  depends  on  the  quality  of  the  food, 
the  form  in  which  it  is  given,  the  condition  of  the 
animal  to  which  it  is  fed,  and  other  circumstances 
which  the  intelligent  farmer  understands. 


APPENDIX. 


The  following  simple  directions  are  given  for  the  benefit 
of  those  who  have  no  experience  in  science-teaching : 

The  exhibition  of  specimens  of  soils,  plants,  fertilizers, 
etc.,  and  the  performance  of  even  a  few  experiments,  will 
av/aken  in  the  minds  of  pupils  a  lively  interest  in  the  sub- 
ject, cultivate  the  power  of  observation,  and  render  the 
work  of  teaching  pleasant  and  practical.  Many  illustra- 
tions, in  addition  to  those  mentioned,  will  doubtless  suggest 
themselves  to  the  minds  of  teachers. 

The  figures  refer  to  corresponding  numbers  in  the 
text : 

(i .)  Show  to  the  class  a  specimen  of  soil,  place  a  little 
on  the  end  of  a  table-knife  or  spatula,  and  heat  it  over  an 
alcohol-lamp  until  the  organic  matter  is  burned  off. 

(2.)  Exhibit  to  the  class  a  sample  of  alluvial  soil  from  a 
creek  or  river  bottom. 

(3.)  Exhibit  pieces  of  sulphur,  carbon,  phosphorus,  iron, 
lead,  silver,  etc.,  to  illustrate  what  is  meant  by  an  element. 

(4.)  Pulverize  in  a  mortar  a  small  quantity  of  potassium 
chlorate,  and  mix  with  it  about  one-fourth  its  weight  of 
manganese  dioxide  (black  oxide  of  manganese).  Place  the 
mixture  in  a  test-tube  or  small  glass  flask,  and  apply  the 
heat  of  an  alcohol-lamp.  Oxygen  will  be  disengaged,  as 
may  be  shown  by  lowering  into  the  flask  or  test-tube  a 
lighted  splinter.    The  flame  will  be  greatly  increased,  and. 


APPENDIX. 


91 


if  blown  out,  and  the  splinter  be  again  thrust  into  the  flask, 
provided  a  spark  be  left,  it  will  burst  into  flame.  If  a  piece 
of  red-hot  charcoal  or  burning  sulphur  be  lowered  into  the 
flask,  it  will  bum  with  great  energy. 

(5.)  Place  a  few  scraps  of  zinc  in  a  deep  wineglass,  and 
pour  over  them  a  little  water.  Now  pour  in  a  little  hydro- 
chloric or  sulphuric  acid,  and  bubbles  of  hydrogen  will  rise 
through  the  liquid.  Bring  a  lighted  match  to  the  mouth  of 
the  wineglass,  and  a  slight  explosion  will  ensue,  caused  by 
the  union  of  the  escaping  hydrogen  with  oxygen  of  the  air 
By  placing  the  zinc  and  acid  in  a  bottle  supplied  with  a 
cork  and  glass  tube,  the  hydrogen  may  be  burned  as  it 
issues  from  the  tube,  or  may  be  collected  in  a  receiver  over 
a  pneumatic  cistern.  Be  very  careful  not  to  light  the  escap- 
ing hydrogen  until  all  the  air  has  been  expelled  from  the 
bottle,  as  a  mixture  of  hydrogen  with  oxygen  contained  in 
air  unites  with  an  explosion  on  application  of  flame.  It  is 
always  best  to  surround  the  bottle  with  a  towel  or  handker- 
chief before  lighting  the  hydrogen.  An  explosion  can  then 
produce  no  bad  effects. 

(6.)  Remove  the  cork,  and  thrust  a  lighted  splinter  into 
the  bottle  ;  a  slight  explosion  will  occur,  the  splinter  will  be 
extinguished,  and  again  lighted  as  it  is  taken  out,  while  the 
hydrogen  will  continue  to  bum  at  the  mouth  of  the  bottle. 
A  small  piece  of  burning  candle  lowered  into  the  bottle 
will  show  these  results  to  better  advantage. 

(7.)  Hold  a  tumbler  or  other  glass  vessel  over  the  flame 
of  burning  hydrogen,  and  the  water  produced  will  condense 
on  the  cool  surface. 

(8.)  Dissolve  some  sugar  or  salt  in  a  tumbler  of  water. 

(9.)  Float  a  piece  of  cork  on  the  surface  of  water,  and 
place  on  it  a  small  pellet  of  phosphorus.  Now  light  the 
phosphorus,  and  cover  it  quickly  with  a  glass  receiver  or 


92 


SCIENTIFIC  AGRICULTURE, 


wide-mouthed  bottle,  the  mouth  dipping  under  the  surface 
of  the  water.  After  the  phosphorus  has  ceased  burning, 
the  water  will  absorb  the  white  fumes  of  the  phosphorus 
oxide,  and  rise  in  the  bottle.  The  gas  which  remains  is 
nearly  pure  nitrogen.  A  lighted  splinter  or  candle  if  brought 
into  the  nitrogen  will  be  extinguished. 

(lo.)  Rub  together  in  a  mortar  a  little  ammonium  chlo- 
ride (sal-ammoniac)  and  quicklime.  Ammonia  will  be  given 
off,  which  can  be  detected  by  its  pungent  odor.  Bring  a 
piece  of  red  litmus-paper  in  contact  with  this  gas,  and  it 
will  turn  blue  immediately. 

(ii.)  Place  a  few  bits  of  copper  in  a  wineglass,  and 
pour  over  them  a  Httle  nitric  acid.  Red  fumes  of  nitrogen 
tetroxide  will  be  formed.  The  blue  liquid  that  is  left  con- 
tains copper  nitrate. 

(i2.)  Dip  a  piece  of  paper  in  spirits  of  turpentine  and 
light  it.  The  black  smoke  consists  of  finely  divided  carbon. 
Hold  a  piece  of  window-glass  over  the  flame  of  a  candle, 
pushing  it  down  upon  the  flame,  and  it  will  soon  be  coated 
with  carbon. 

(13.)  Place  some  small  pieces  of  marble  or  limestone  in 
a  deep  wineglass  or  bottle,  and  pour  over  them  a  little 
hydrochloric  acid.  The  brisk  effervescence  that  takes  place 
is  caused  by  the  escape  of  carbon  dioxide.  A  burning 
splinter  or  candle  will  be  extinguished  if  lowered  into  the 
bottle. 

(14.)  Bum  a  small  piece  of  sulphur,  and  hold  a  red  rose 
or  other  flower  over  the  fumes.  The  flower  will  be  bleached. 
A  similar  effect  may  be  produced  with  a  sulphur-match. 

(15.)  Place  a  splinter  of  wood  in  strong  sulphuric  acid, 
and  it  will  turn  black.  The  acid  does  not  act  on  the  car- 
bon of  the  wood.  Pour  a  little  of  the  strong  acid  into  a 
wineglass  of  water,  and  the  water  will  become  very  hot, 


APPENDIX. 


93 


caused  by  its  union  with  the  acid.  Caution  should  be  ob- 
served in  pouring  this  acid  into  water,  and  care  be  taken 
not  to  pour  the  water  into  the  acid. 

(i6.)  Exhibit  a  piece  of  phosphorus,  and  show  how 
easily  it  can  be  set  on  fire. 

(17.)  Rub  a  match,  and  show  how  the  friction  causes  it 
to  inflame. 

(18.)  Place  a  little  phosphorus  on  a  dry  plate,  set  it  on 
fire,  and  quickly  place  over  it  a  receiver,  or  wide-mouthed 
bottle.  The  white  fumes  that  rise  are  phosphorus  pent- 
oxide.  Water  unites  with  this  oxide  to  form  phosphoric 
acid. 

(19.)  Place  some  manganese  dioxide  (black  oxide  of 
manganese)  in  a  glass  flask  or  test-tube,  pour  over  it  some 
strong  hydrochloric  acid,  and  apply  a  gentle  heat.  Chlo- 
rine, a  yellowish-green  gas,  will  be  disengaged.  By  means 
of  a  properly  bent  glass  tube  reaching  to  the  bottom  of  a 
bottle,  this  gas  may  be  collected  by  displacement.  Im- 
merse in  it  a  lighted  taper  or  splinter,  and  the  light  will  be 
extinguished.  A  red  rose  moistened  and  placed  in  a  bot- 
tle of  chlorine  will  be  bleached  in  a  short  time. 

(20.)  Heat  in  a  test-tube,  or  small  flask,  a  little  potas- 
sium iodide,  manganese  dioxide,  and  sulphuric  acid.  The 
beautiful  violet-colored  vapor  of  iodine  will  be  disengaged. 
Substitute  potassium  bromide  for  the  potassium  iodide,  and 
the  deep-red  vapor  of  bromine  will  be  given  off. 

(21.)  Drop  a  small  piece  of  potassium  on  the  surface  of 
water.  The  metal  will  bum  with  a  violet  flame.  Place  a 
small  piece  of  potassium  on  the  wick  of  an  alcohol-lamp, 
touch  it  with  a  piece  of  ice,  and  the  lamp  will  be  lighted. 

(22.)  Drop  a  piece  of  sodium  on  the  surface  of  water. 
It  will  move  around,  decomposing  the  water  with  the  dis- 
engagement of  hydrogen.     Place  a  piece  in  a  few  drops  of 


54  SCIENTIFIC  AGRICULTURE. 

water  sprinkled  on  a  board,  and  the  sodium  will  burst  into 
flame  of  a  deep-yellow  color. 

(23.)  Color  some  water  blue  with  litmus.  Add  a  drop 
of  acid  to  turn  it  red,  and  then  drop  a  piece  of  potassium 
or  sodium  on  the  surface.  The  blue  color  will  be  restored 
as  the  metal  is  consumed. 

(24.)  Heat  in  the  flame  of  an  alcohol-lamp  a  piece  of 
magnesium  ribbon,  and  show  the  brilliancy  of  its  combus- 
tion. 

(25.)  Collect  samples  of  different  varieties  of  soils,  and 
exhibit  them  to  the  class. 

(26.)  Heat  some  green  leaves  or  grass  on  a  spatula,  me- 
tallic plate,  or  small  shovel,  until  nothing  is  left  but  the  ash. 

(27.)  Exhibit  specimens  of  sugar,  starch,  albumen,  or 
white  of  ^g%,  etc. 

(28.)  Pour  some  clear  lime-water  into  a  wineglass,  and 
by  means  of  a  straw  or  glass  tube  breathe  through  the 
liquid.  The  milky  appearance  is  caused  by  the  carbon 
dioxide  from  the  lungs  combining  with  the  lime,  and  form- 
ing insoluble  calcium  carbonate. 

(29.)  Collect,  and  show  to  the  class,  a  few  plants  with 
root,  stem,  and  leaves. 

(30.)  Pour  some  water  on  a  lump  of  unslaked  lime. 
In  a  few  minutes  the  mass  will  become  hot,  combine  with 
a  portion  of  the  water,  and  crumble  into  powder. 

(31.)  Pour  some  hydrochloric  acid  on  marl,  and  effer- 
vescence will  take  place,  caused  by  the  escape  of  carbon 
dioxide. 

(32.)  Mix  a  tablespoonful  of  plaster  of  Paris  with  a  lit- 
tle water,  and  show  how  it  sets,  or  hardens. 

Exhibit  to  the  class  specimens  of  as  many  different  fer- 
tilizers as  can  be  obtained. 


QUESTIONS. 


The  following  questions  are  intended  merely  to  direct 
attention  to  the  more  important  points  in  the  text.  Intelli- 
gent teachers  will  not,  of  course,  confine  themselves  to  any 
set  form  of  questions,  but  secure  as  far  as  possible  a  mas- 
tery of  the  subject. 

CHAPTER   I. 

THE   DEVELOPMENT   OF   SCIENTIFIC   AGRICULTURE. 

1.  What  is  agriculture?  As  an  art,  what  does  it  teach? 
What,  as  a  science  ? 

2.  How  does  it  rank  as  an  industrial  pursuit  ?  Why  has  it 
always  been  first  in  importance  ? 

3.  Why  was  less  cultivation  of  the  soil  required  in  the  early 
ages  of  the  world  ?  Where  did  men  obtain  food  and  clothing  ? 
What  effect  had  the  increase  of  population  ? 

4.  What  is  said  of  the  progress  of  agriculture  as  a  science  ? 
Why  do  some  men  say  that  practicai  and  scientific  farming  are 
different  ? 

5.  Why  has  the  progress  of  agriculture  as  a  science  been 
slow  ?  What  great  men  are  mentioned  as  having  been  farmers 
or  having  written  on  farming?  What  is  necessary  to  accomplish 
great  results  in  any  science  ? 

6.  What  other  reason  is  given  for  the  slow  progress  of  agri- 
culture as  a  science  ?  What  is  botany  ?  Why  should  a  farn.er 
know  something  of  it  ? 


^6  SCIENTIFIC  AGRICULTURE. 

7.  What  is  zoSlogy  ?  Why  should  the  farmer  know  some- 
thing of  this  science?  What  does  geology  treat  of ?  Why 
should  the  farmer  study  it?  With  what  does  the  mechanic 
supply  the  farmer?  What  does  physics  treat  of?  Why  should 
the  farmer  have  some  knowledge  of  chemistry  ? 

8.  Why  should  the  farmer  have  a  general  acquaintance  with 
the  sciences  mentioned  ?  What  relation  do  they  sustain  to  agri- 
culture ? 

g.  What  sciences  are  of  most  importance  to  the  farmer? 
What  improvements  in  farming  implements  are  mentioned? 

10.  What  benefits  has  agriculture  derived  from  chemistry? 

11.  How  does  the  chemist  proceed  in  his  investigations? 
What  is  it  proposed  to  show  ? 

CHAPTER   II. 

THE  ORIGIN,   COMPOSITION,    AND  CLASSIFICATION   OF   SOILS. 

12.  What  is  the  soil?  Of  what  does  it  consist?  Where 
does  the  organic  matter  come  from  ?  When  burned,  what  is 
left  ?  What  do  geologists  suppose  the  earth  to  have  once  been  ? 
What  happened  as  it  cooled  down  ?     Of  what  does  soil  consist  ? 

13.  What  is  meant  by  mechanical  agencies  ?  What  by 
chemical?  Give  examples?  Are  these  agencies  always  at 
work? 

14.  What  is  included  under  the  term  ' '  rock "  ?  What 
agencies  disintegrate  rocks?  How  does  water  act?  How 
does  thorough  cultivation  hfelp  this  disintegrating  action  ? 

15.  With  what  do  the  elements  of  a  soil  vary  ?  Does  the  soil 
always  rest  on  the  rock  from  which  it  was  formed  ?  What  is  an 
alluvial  %oA'i 

16.  What  causes  the  difference  in  the  quality  of  soils  ?  Are 
there  many  simple  substances  ? 

17.  How  many  elements  are  certainly  known  ?  Which  are 
gases  ?     Liquids  ?     Solids  ?     Are  there  any  permanent  gases  ? 

18.  How  many  elements  are  concerned  in  the  growth  of 


QUESTIONS.  97 

plants?    Name  the  non-metallic  elements.    The  metals.    What 
other  elements  are  sometimes  present? 

19.  What  is  said  of  oxygen  ?  How  prepared  ?  What  should 
be  mixed  with  the  potassium  chlorate  ? 

20.  Properties  of  oxygen  ?  What  is  combustion  ?  Give  ex- 
amples. 

21.  With  what  elements  does  oxygen  unite?  What  are 
these  compounds  called?  How  named?  What  is  potash? 
What  is  lime  ? 

22.  Give  cases  of  oxidation  without  light  and  intense  heat? 
What  happens  in  breathing?  Can  animals  live  without  oxy- 
gen ?     Can  plants  ? 

23.  What  is  said  of  hydrogen?     How  is  it  prepared? 

24.  Properties  of  hydrogen  ?     Result  of  its  combustion  ? 

25.  How  is  water  formed  ?  What  does  it  form  when  con- 
densed in  the  air?  Where  do  natural  waters  get  the  mineral  mat- 
ter contained  in  them  ?  What  kind  of  water  is  the  purest?  Why? 

26.  Where  is  nitrogen  found  ?  How  much  is  in  the  air  ? 
How  is  it  prepared  ? 

27.  Properties  of  nitrogen?  Is  it  poisonous?  How  can 
oxygen,  hydrogen,  and  nitrogen,  be  distinguished  ? 

28.  What  is  ammonia?  How  made?  How  much  does 
water  absorb  ?  What  is  hartshorn  ?  Why  is  ammonia  called 
an  alkali  ? 

29.  How  is  ammonia  formed  naturally?  How  does  it  get 
into  plants  ? 

30.  What  is  nitric  acid  ?  What  does  it  form  with  metals  ? 
What  is  nitre?    Chili  saltpetre?     How  used? 

31.  In  what  forms  does  carbon  exist?  Is  it  abundant  in 
plants?  What  per  cent,  in  sugar?  In  turpentine?  What 
makes  smoke  black  ? 

32.  What  is  carbon  dioxide  ?  Where  found  ?  What  are  its 
properties  ? 

33.  What  is  silicon?  Is  it  necessary  to  plants?  Where 
is  it  found  ? 


98  SCIENTIFIC  AGRICULTURE. 

34.  What  is  sulphur  ?  What  does  it  form  in  burning  ?  Its 
use  ?  What  is  sulphuric  acid  ?  What  are  its  compounds 
called?     Give  examples. 

35.  What  is  phosphorus  ?  Where  found  ?  Why  must  it  be 
kept  under  water?     Its  use  ?     How  does  a  match  bum  ? 

36.  What  is  phosphoric  acid  ?  What  is  calcium  phosphate  ? 
What  does  it  form  ?  Why  must  soil  contain  phosphorus  ? 
How  can  it  be  supplied  ? 

37.  What  is  chlorine?  What  is  hydrochloric  acid?  How 
is  chlorine  separated ?     Its  properties?     Uses?    Where  found? 

38.  What  is  iodine  ?  Bromine  ?  To  what  are  they  similar? 
Properties  of  fluorine  ?    Where  found  ? 

39.  What  is  potassium?  How  kept?  Why?  What  effect 
has  water  on  it  ?  What  is  caustic  potash  ?  What  do  all  acids 
contain  ?     How  are  salts  of  potassium  formed  ?    Where  found  ? 

40.  Describe  sodium.  How  does  it  act  on  water  ?  What 
is  common  salt  ?  Where  found  ?  In  what  respects  are  caustic 
potash  and  soda  similar  to  ammonia  ?     Their  use  ? 

41.  Describe  calcium  ?  Lime  ?  What  are  marble,  lime- 
stone, and  chalk  ?     How  changed  to  lime  ?     What  is  gypsum  r 

42.  Describe  magnesium  and  aluminum.  Where  found  ? 
What  are  its  properties  ? 

43.  Ores  of  iron  ?  For  what  purpose  used  ?  Where  is  iron 
found  ?    What  is  said  about  manganese  ? 

44.  How  is  the  composition  of  a  soil  generally  given  ?  Is 
it  easy  to  analyze  a  soil  ? 

45.  What  constituent  exists  in  the  largest  proportion  in  the 
analysis  given  ?     What  in  the  smallest  ? 

46.  How  much  organic  matter  is  found  in  soils  ?  What  ele- 
ments are  likely  to  be  deficient  ? 

47.  How  may  soils  be  classified  ? 

48.  What  are  calcareous  soils  ?     Peaty  ?     Heavy  ?    Light  ? 

49.  How  deep  is  the  soil  generally  ?  What  is  the  sub-soil  i" 
How  may  the  depth  of  soil  be  increased  ?    Its  advantages  ? 


QUESTIONS.  gj 

CHAPTER   III. 

THE  COMPOSITION   OF  PLANTS. 

50.  How  many  elements  are  found  in  plants  ?  What  are 
they? 

51.  What  element  in  soils  is  not  in  plants  ?  What  in  plants 
and  not  in  animals  ? 

52.  What  effect  has  heat  on  plants  ?  How  much  water  in 
turnips,  cabbages,  and  potatoes  ?    In  cured  hay  ?   What  is  ash  ? 

53.  What  four  elements  are  consumed  when  a  plant  is 
burned  ?    Why  called  organic  ?     What  becomes  of  them  ? 

54.  What  becomes  of  phosphorus  and  sulphur?  Chlorine 
and  silicon  ?  How  much  ash  in  wood  ?  In  tobacco  ?  Com  ? 
Which  has  in  it  the  most  phosphorus  oxide,  the  ash  of  com  or 
potatoes  ?    Chlorine  ?     Potassium  oxide  ? 

55.  What  are  ultimate  elements  ?   Proximate  ?    Name  some. 

56.  What  are  amylaceous  and  saccharine  substances  ?  Of 
what  elements  are  they  composed  ?  Where  is  cellulose  found  ? 
How  converted  into  sugar  ? 

57.  What  are  pectose  substances  ?    Where  found  ? 

58.  Name  some  vegetable  acids.     What  elements  in  them  ? 

59.  Where  are  fats  and  oils  found  ?  How  do  they  differ 
from  sugar  ?    What  else  are  included  in  this  group  ? 

60.  How  do  the  albuminoid  or  protein  groups  differ  from 
those  mentioned  ?  Where  is  pure  albumen  found  ?  What  do 
botanists  mean  by  "  albumen  "  ?  Where  is  gluten  found  ? 
Vegetable  casein  ? 

61.  How  many  elements  are  in  these  compounds  ?  What 
has  a  knowledge  of  their  chemical  constitution  done  ? 

62.  How  do  starch  and  sugar  differ  ?  Where  is  starch 
found  ? 

63.  How  does  grape-sugar  differ  from  starch  ?  Where  does 
the  change  of  one  into  the  other  take  place  ?  How  can  cotton 
be  changed  into  sugar? 

64.  What  takes  place  in  the  leaf  ? 


lOO  SCIENTIFIC  AGRICULTURE. 

65.  Which  crop  mentioned  in  the  table  has  the  most  starch  ? 
Albuminoids  ?    Fat  ?    Woody  fibre  ?    Ash  ? 

66.  Are  the  ash  constituents  important  ?  What  becomes 
of  the  products  of  combustion  ?  What  does  a  plant  carry  from 
the  soil  ?     What  is  the  ultimate  effect  ? 

67.  What  does  Liebig  mean  by  a  system  of  spoliation  ? 
What  elements  are  scarcely  ever  deficient  ?  In  what  condition 
may  they  exist  ?     How  can  this  be  remedied  ? 

68.  What  elements  are  likely  to  be  deficient  ?  Can  the  soil 
produce  when  any  of  the  essential  elements  of  plants  are  ab- 
sent ? 

69.  What  does  chemistry  teach  the  farmer  ?  For  what 
must  it  not  be  held  responsible  ? 

70.  By  what  must  the  farmer  be  guided  ? 

CHAPTER   IV. 

THE  COMPOSITION  AND   PROPERTIES  OF  THE  ATMOSPHERE. 

71.  What  does  the  atmosphere  contain  ? 

72.  Is  the  air  uniform  in  composition  ?  In  what  condition 
are  its  constituents  ? 

73.  What  is  said  of  watery  vapor  ?  Whence  does  it  rise  ? 
What  does  it  form  when  condensed  ? 

74.  The  character  of  nitrogen  ?  Of  oxygen  ?  The  effect 
of  carbon  dioxide  on  animals  ?     On  plants  ? 

75.  How  is  carbon  dioxide  formed  ?  What  prevents  its  ac- 
cumulation in  the  atmosphere  ?  What  change  takes  place  in 
it  when  absorbed  by  the  leaves  of  plants  ? 

76.  How  does  carbon  dioxide  get  into  the  leaves  ?  Through 
what  influence  is  it  decomposed  ? 

77.  How  much  carbon  dioxide  exists  in  the  atmosphere  ? 
What  says  a  distinguished  chemist  ? 

78.  How  much  ammonia  is  in  the  atmosphere  ? 

79.  To  what  is  the  atmosphere  adapted  ?  What  benefits 
are  derived  from  it  ? 


QUESTIONS.  lOi 

80.  What  does  science  teach  in  reference  to  the  atmospheric 
agencies  ?  To  what  do  they  contribute  ?  The  effect  of  their 
action  on  solid  substances  ? 

81.  The  effect  of  the  atmosphere  on  organic  and  inorganic 
matter  ?     On  a  dead  animal  or  plant  ? 

82.  What  knowledge  is  necessary  to  understand  the  growth 
and  development  of  plants  ? 

CHAPTER   V. 
THE  SOURCES  OF   PLANT-FOOD  AND   HOW   OBTAINED. 

83.  The  sources  of  plant-food  ?  What  elements  are  found 
in  air  ? 

84.  Why  cannot  carbon  enter  the  plant  in  a  pure  state  ?  In 
what  form  is  it  a  gas  ?  How  does  it  enter  ?  Why  do  plants 
grow  faster  in  daytime  than  at  night  ?  Where  does  the  carbon 
of  plants  come  from  ? 

85.  How  do  hydrogen  and  oxygen  get  into  plants  ? 

86.  How  nitrogen  ?  Does  free  nitrogen  contribute  to 
growth  ?    Where  is  it  gotten  ? 

87.  How  much  nitrogen  do  plants  contain  ?  How  much  is 
in  a  ton  of  hay  ?  Why  must  it  be  supplied  in  the  form  of  salts 
containing  nitrogen  ? 

88.  Why  are  the  four  elements  mentioned  called  organic  ? 
What  are  the  other  constituents  called  ?  How  do  they  get  into 
plants  ?     In  what  form  ? 

89.  What  are  the  main  parts  of  a  plant  ?  What  does  the 
seed  contain  ?  What  does  it  require  for  germination  ?  How 
does  it  germinate  ? 

90.  How  does  the  root  grow  ?  What  may  be  regarded  as 
the  lungs  of  a  plant  ?  What  the  mouth  ?  What  is  said  of  the 
roots  spreading  ?  What  is  necessary  for  a  plant  to  be  thrifty  ? 
Why  must  its  food  be  near  at  hand  ? 

91.  How  did  Schubert  determine  the  extent  of  the  roots  of 
plants  ?  How  deep  did  he  find  the  roots  of  wheat  to  extend  ? 
What  is  the  total  length  of  the  roots  of  a  barley-plant  ? 


loa  SCIENTIFIC  AGRICULTURE. 

92.  What  increases  the  absorbing  surface  of  roots  ?  Are 
there  such  organs  as  "  spongioles  "  ? 

93.  How  many  kinds  of  roots  are  there  ?  What  is  said  of 
the  mulberry-tree  ?    What  of  cornstalks  ? 

94.  Have  roots  the  power  of  "excretion"?     Of  selection? 

95.  What  is  evident  from  what  has  been  said  about  roots  ? 
By  what  should  the  farmer  be  guided  ? 

CHAPTER  VI. 

THE  IMPROVEMENT  OF  SOILS. 

96.  What  power  has  inert  matter?  What  has  the  seed? 
Do  we  know  what  the  life-principle  is  ? 

97.  Do  we  understand  the  connection  between  the  growth 
of  a  plant  and  its  surroundings  ?    What  has  chemistry  taught  ? 

98.  What  is  necessary  to  insure  fertility  ?  What  vague  no- 
tions have  some  men  ? 

99.  What  have  some  writers  asserted  ?  Is  it  true  ?  What 
can  we  not  control  ? 

100.  What  has  science  done  ? 

loi.  What  of  sewage  ?  What  does  a  perfect  system  of  agri- 
culture require  ? 

102.  Upon  what  are  all  scientific  methods  founded  ?  To 
what  addressed  ?  What  soil  cannot  be  improved  ?  What  can 
be? 

103.  What  means  can  be  used  for  the  improvement  of  soils  ? 
What  are  mechanical?  What  chemical?  The  effect  of  the 
first  ?    Of  the  second  ? 

104.  What  system  of  drainage  is  the  cheapest  ? 

105.  What  are  the  benefits  of  drainage? 

106.  What  are  the  advantages  of  deep  plowing  and  sub- 
soiling  ? 

107.  What  additional  advantage  is  mentioned  ?  What  care 
should  be  taken  ? 

108.  Mention  aa  economical  and  effective  method  of  sub- 
soiUng. 


QUESTIONS.  103 

109.  What  other  mechanical  means  of  improvement  are  men- 
tioned ?  What  is  the  great  object  to  be  accomplished  ?  What, 
feeling  generally  prevails  in  a  new  country  ? 

no.  Is  thorough  cultivation  always  proper? 

CHAPTER   VII. 

THE   USE  OF   MANURES,   OR   FERTILIZERS. 

III.  Upon  what  principles  is  the  use  of  fertilizers  based  ? 
1x2.  When  should  fertilizers  be  used  ? 

113.  What  produces  exhaustion?  How  much  potash  is  re- 
moved in  a  ton  of  red-clover  hay  ?  How  much  phosphoric  acid  ? 

114.  How  much  phosphoric  acid  is  contained  in  an  ox 
weighing  1,000  pounds  ?  How  much  potash  in  1,000  pounds 
of  unwashed  wool  ? 

115.  Upon  what  does  the  rapidity  of  exhaustion  depend  ?  Is 
it  sure  to  follow  without  restoration  ? 

116.  How  many  kinds  of  fertilizers  are  there  ? 

117.  Why  is  a  decaying  plant  a  good  fertilizer  ?  How  do 
vegetable  substances  benefit  land  ? 

118.  How  do  cornstalks  serve  as  a  fertilizer? 

119.  What  is  said  of  cotton-seed  ?     Leaves  ? 

120.  What  two  important  constituents  are  found  in  cotton- 
seed ?  How  much  mineral  matter  in  a  bale  of  lint  ?  In  cot- 
ton-seed from  a  bale  ? 

121.  If  the  seed  be  returned  to  the  soil,  is  cotton  an  exhaus- 
tive crop  ?  What  escapes  from  fermenting  seed  ?  Why  should 
it  be  preserved  ? 

122.  How  should  seed  be  applied  ? 

123.  Is  the  oil  in  cotton-seed  valuable  as  a  fertilizer  ?  Why 
not? 

124.  What  are  the  good  effects  of  grinding  the  seed  ?  How 
can  its  constituents  be  preserved  ? 

125.  What  important  object  should  be  accomplished  on 
every  farm  ? 


I  ©4 


SCIENTIFIC  A  GRICUL  TURE. 


126.  What  are  animal  fertilizers  ?    Are  they  valuable  ? 

127.  What  is  said  of  the  bones  and  excrements  of  animals  as 
fertilizers  ? 

128.  What  is  the  composition  of  bones  ? 

129.  How  are  they  sometimes  used  ? 

130.  How  are  they  converted  into  superphosphate  ? 

131.  What  does  sulphuric  acid  form  with  calcium  ? 

132.  Where  has  a  large  deposit   of  bone  phosphate  been 
found  ? 

133.  What  other  source  of  superphosphate  is  mentioned  ? 

134.  How   can   a  good   superphosphate   be   made    by   the 
iarmer  ? 

135.  Give  the  directions  of  Dr.  Nichols  for  making  it. 

136.  What  is  said  of  guano  and  its  use  in  South  America  ? 

137.  What  is  guano  ? 

138.  When  was  it  introduced  into  Europe  ? 

139.  What  does  Liebig  say  of  its  use  ? 

140.  When  was  it  brought  to  the  United  States  ? 

141.  Why  is  the  Peruvian  guano  the  best  ? 

142.  What  makes  guano  so  rich  a  fertilizer  ? 

143.  Give  the  composition  of  guano. 

144.  How  does  Peruvian  guano  differ  from  the  African  ? 

145.  Give  its  properties. 

146.  To  what  is  its  stimulating  effect  due  ? 

147.  What  retards  the  growth  of  plants  ?     Is  nitrogen  sup- 
plied from  the  air  ? 

148.  How  does  guano  act  ?     Why  does  it  sometimes  "  run 
out "  ? 

149.  With  what  sort  of  fertilizers  is  it  generally  mixed  ? 

150.  Why  should  it  not  be  placed  next  to  the  seed  ? 

151.  What  is  mentioned  as  a  good  mixture?     How  should 
it  be  applied  ? 

152.  Should  guano  be  mixed  with  lime  ?     Why  not  ? 

153.  What  is  said  of  farm-yard  manure  ? 

154.  Upon  what  does  its  value  depend  ?     How  can  the  es- 
cape of  ammonia  be  determined  ?     How  prevented  ? 


QUESTIONS.  105 

155.  How  should  manure-heaps  be  managed  ?   What  should 
be  added  ? 

156.  What  is  said  of  human  excrements  ? 

157.  Why  are  animal  manures  richer  than  vegetable  ? 

CHAPTER  Vni. 

MINERAL  FERTILIZERS. 

158.  What  mineral  fertilizers  are  mentioned  ? 

159.  How  is  lime  made  ? 

160.  What  is  slaked  lime  ?     What  effect  on  it  has  long  ex- 
posure to  air  ? 

161.  In  what  condition  is  the  water  in  slaked  lime?    Its 
properties  ?     How  does  mortar  harden  ? 

162.  What  is  the  use  of  lime  as  a  fertilizer  ? 

163.  What  is  marl  ?     How  valued  ? 

164.  What  is  said  of  green-sand  marl  ?      Composition  of 
marl  ? 

165.  What  sort  of  lands  are  well  suited  for  marl  ? 

166.  What   is  gypsum  ?    What   effect  has  heat   upon   it  ? 
How  does  it  harden  ?     Its  use  ? 

167.  How  found  ?     Its  properties  ?     How  applied  ? 

168.  Why  does  it  not  injure  seeds  ?    Why  should  it  not  be 
mixed  with  superphosphate  ? 

l6g.  What  is  common  salt  ?     How  does  it  act  ? 

170.  What  are  salts  ?     What  is  said  of  the  utilization  of 
waste  products  ? 

171.  How  much  potash  in  the  ashes  of  the  oak  ?    Beech  ? 

172.  Why  are  ashes  a  good  fertilizer? 

173.  What  is  a  compost  ?     How  made  ? 

174.  What  directions  are  given  by  Pendleton  for  compost- 
mg  with  cotton-seed  ? 

175.  How  can  a  good  compost  be  made  from  materials  on 
every  farm  ? 

176.  What  does  Professor  Ville  call  a  "  complete  manure"? 


I06  SCIENTIFIC  AGRICULTURE. 

CHAPTER   IX. 

ROTATION  OF  CROPS. 

177.  What  is  meant  by  rotation  ? 

178.  What  are  its  advantages  ?     Give  illustrations. 

179.  What  other  advantage  is  mentioned  ? 

180.  Give  a  third  advantage  of  rotation. 

181.  Give  a  fourth  advantage. 

182.  What  is  said  of  change  of  seed  ? 

183.  What  crops  should  not  follow  each  other  ?  What  prin- 
ciple should  govern  ? 

184.  Mention  a  good  three  years'  rotation.  A  four  years' 
rotation.     An  English  rotation. 

185.  A  rotation  for  the  tobacco-planter.     For  cotton-planter. 
186    What  is  best  to  be  done  with  the  clover  ?     Why  ? 

187.  Have  plants  the  power  of  secretion  ?     Of  selection  ? 

188.  When  will  rotation  certainly  fail  ?  How  can  such 
land  be  restored  ? 

CHAPTER  X. 

THE  SELECTION   AND  CARE  OF  LIVE-STOCK. 

189.  Why  must  every  farmer  have  live-stock  ? 

190.  Upon  what  will  the  kind  of  stock  to  be  kept  depend  ? 
What  sort  should  be  selected  ?    Why  ? 

191.  What  is  necessary  in  the  management  of  live-stock  ? 
Why?  How  should  it  be  fed?  Why  should  exposure  be 
avoided  ? 

192.  Difference  between  the  functions  of  plants  and  animals  ? 

193.  How  do  animals  digest  their  food  and  convert  it  into 
bone  and  muscle  ? 

194.  What  gas  is  formed  in  respiration  ?     How  shown  ? 

195.  Why  should  animals  require  more  food  in  cold  than  in 
warm  weather  ?    Why  more  when  at  work  ? 


QUESTIONS.  107 

196.  What  is  Liebig's  division  of  food  ?     Is  his  theory  strict- 
ly true  ? 

197.  "What  sort  of  food  do  young  animals  need  ? 

198.  What  first  wastes  away  when  an  animal  is  not  fed? 
Why  do  animals  protected  from  cold  fatten  faster  ? 

199.  What  is  the  chief  constituent  of  bones  ?     Whence  de- 
rived ? 

200.  How  does  wheat-straw  compare  with  hay  as  a  food  for 
stock  ?     Upon  what  do  the  good  effects  of  food  depend  ? 


THE    END. 


Gray's  Series  of  Botanies 

By  the  late  ASA  GRAY,  LL.D.,  of  Harvard  University. 

FOR  ELEMENTARY  AND  GRAMMAR  SCHOOLS 

GRAY'S  HOW  PLANTS  GROW.   With  a  Popular  Flora    $0.80 
A  simple  introduction  to  the  study  of  Botany. 

GRAY'S  HOW  PLANTS  BEHAVE 54 

Botany  for  Young  People. 

FOR  SECONDARY  SCHOOLS 

GRAY'S  LESSONS  IN  BOTANY.     Revised  Edition      .         .94 
The  standard  text-book  for  schools  and  colleges. 

GRAY'S  FIELD.  FOREST,  AND  GARDEN  BOTANY     .       1.44 
A  full  description  and  flora  of  the  common  plants.   Revised. 

GRAY'SSCHOOL  AND  FIELD  BOOK  OF  BOTANY      .       1.80 
Comprising  the  "  Lessons  "  and  "  Field,  Forest,  and  Garden 
Botany  "  in  one  vol.     Revised. 

FOR  COLLEGES  AND  ADVANCED  STUDENTS 

GRAY'S  MANUAL  OF  BOTANY 1.62 

A  full  description  and  flora  of  plants  for  the  Northern 

United  States,  east  of  the  Mississippi.     Revised. 

The  Same.     Tourist's  Edition        ....       2.00 

GRAY'S  LESSONS  AND  MANUAL  OF  BOTANY  2.16 

Comprising  the  "  Lessons  in  Botany"  and  the  "  Manual " 
in  one  vol.     Revised. 

GRAY'S  BOTANICAL  TEXT-BOOK 

L  Gray's  Structural  Botany 2.00 

IL  Goodale's  Physiological  Botany        .         .         .       2.00 


Copies  sent,  prepaid,  on  receipt  of  the  price, 

American    Book   Company 

NEW  YORK  ♦  CINCINNATI  ♦  CHICAGO 

(S.  171) 


Aids    to    Field    and    Laboratory 
Work   in   Botany 


APGARS'  PLANT  ANALYSIS 55  cents 

A  book  of  blank  schedules,  adapted  to  Gray's  Botanies, 
for  pupils'  use  in  writing  and  preserving  brief  systematic 
descriptions  of  the  plants  analyzed  by  them  in  field  or  class 
work.  Space  is  allowed  for  descriptions  of  about  one  hundred 
and  twenty-four  plants  with  an  alphabetical  index. 

An  analytical  arrangement  of  botanical  terms  is  provided, 
in  which  the  words  defined  are  illustrated  by  small  wood  cuts, 
which  show  at  a  glance  the  characteristics  named  in  the 
definition. 

APGAR'S  TREES  OF  THE  NORTHERN  UNITED  STAJES 

Their  Study,  Description,  and  Determination       .     $1.00 

This  work  has  been  prepared  as  an  accessory  to  the  study 
of  Botany,  and  to  assist  and  encourage  teachers  in  introducing 
into  their  classes  instruction  in  Nature  Study.  The  trees  of 
our  forests,  lawns,  yards,  orchards,  streets,  borders  and  parks 
afford  a  most  favorable  and  fruitful  field  for  the  purposes  of 
such  study.  They  are  real  objects  of  nature,  easily  accessible, 
and  of  such  a  character  as  to  admit  of  being  studied  at  all 
seasons  and  in  all  localities.  Besides,  the  subject  is  one  of 
general  and  increasing  interest,  and  one  that  can  be  taught 
successfully  by  those  who  have  had  no  regular  scientific 
training. 


Copies  will  be  sent,  prepaid,  on  receipt  of  the  price. 

American   Book  Company 

NEW  YORK  ♦  CINCINNATI  ♦  CHICAGO 

(S.  I7«) 


Text-Books  in  Geology 

By  JAMES  D.  DANA,  LL.D. 
Late  Professor  of  Geology  and  Mineralogy  in  Yale  University 


DANA'S  GEOLOGICAL  STORY  BRIEFLY  TOLD      .        $1.15 

A  new  and  revised  edition  of  this  popular  text-book  for 
beginners  in  the  study,  and  for  the  general  reader.  The  book 
has  been  entirely  rewritten,  and  improved  by  the  addition  of 
many  new  illustrations  and  interesting  descriptions  of  the 
latest  phases  and  discoveries  of  the  science.  In  contents  and 
dress  it  is  an  attractive  volume  and  well  suited  for  young 
students. 

DANA'S  REVISED  TEXT-BOOK  OF  GEOLOGY  $1.40 

Fifth  Edition,  Revised  and  Enlarged.  Edited  by  William 
North  Rice,  Ph.D.,  LL.D.,  Professor  of  Geology  in 
Wesleyan  University.  This  is  the  standard  text-book  in 
geology  for  high  school  and  elementary  college  work.  While 
the  general  and  distinctive  features  of  the  original  work  have 
been  preserved,  the  book  has  been  thoroughly  revised,  enlarged, 
and  improved. 

DANA'S  MANUAL  OF  GEOLOGY    ....       $5.00 

Fourth  Revised  Edition.  This  great  work  is  a  complete 
thesaurus  of  the  principles,  methods,  and  details  of  the  science 
of  geology  in  its  varied  branches,  including  the  formation 
and  metamorphism  of  rocks,  physiography,  orogeny,  and 
epeirogeny,  biologic  evolution,  and  paleontology.  It  is  not 
only  a  text-book  for  the  college  student  but  a  handbook  for 
the  professional  geologist.  This  last  revision  was  performed 
almost  exclusively  by  Dr.  Dana  himself,  and  may  justly  be 
regarded  as  the  crowning  work  of  a  long  and  useful  life. 


Copies  sent,  prepaid,  on  receipt  of  the  price. 

American    Book   Company 

NEW  YORK  ♦  CINCmNATI  •  CHICAGO 

(S.  177) 


A    New    Astronomy 

By  DAVID  P.  TODD,  M.A.,  Ph.D. 

Professorof  Astronomy  and  Director  of  the  Observatory,  Amherst  College 
Cloth,  12mo,  480  pages.     Illustrated.     Price  $1.30 


This  book  is  designed  for  classes  pursuing  the  study  of 
Astronomy  in  High  Schools,  Academies,  and  Colleges.  The 
author's  long  experience  as  a  director  in  astronomical  observ- 
atories and  in  teaching  the  subject  has  given  him  unusual 
qualifications  and  advantages  for  preparing  an  ideal  text-book. 

The  noteworthy  feature  which  distinguishes  this  from  other 
text-books  on  Astronomy  is  the  practical  way  in  which  the 
Xibjects  treated  are  reenforced  by  laboratory  experiments 
and  methods.  In  this  the  author  follows  the  principle  that 
Astronomy  is  preeminently  a  science  of  observation  and 
should  be  so  taught. 

By  placing  more  importance  on  the  physical  than  on  the 
mathematical  facts  of  Astronomy  the  author  has  made  every 
page  of  the  book  deeply  interesting  to  the  student  and  the 
general  reader.  The  treatment  of  the  planets  and  other 
heavenly  bodies  and  of  the  law  of  universal  gravitation  is 
unusually  full,  clear,  and  illuminative.  The  marvelous  dis- 
coveries of  Astronomy  in  recent  years,  and  the  latest  advances 
in  methods  of  teaching  the  science,  are  all  represented. 

The  illustrations  are  an  important  feature  of  the  book. 
Many  of  them  are  so  ingeniously  devised  that  they  explain  at 
a  glance  what  pages  of  mere  description  could  not  make  c^ear. 


Copies  sent,  prepaid,  on  receipt  of  the  price. 

American    Book  Company 

NEW   YORK  ♦  CINCINNATI  •  CHICAGO 

(S.  i8i) 


Text-Books  in  Chemistry 


STORER  AND    LINDSAY'S    ELEMENTARY   MANUAL 

OF  CHEMISTRY $1.20 

This  text-book  is  a  thorough  revision  of  Eliot,  Storer,  and 
Nichol's  Elementary  Manual  of  Chemistry,  rewritten  and 
enlarged  to  represent  the  present  condition  of  chemical  knowl- 
edge, and  to  meet  the  demands  for  a  class  book  on  Chemistry, 
for  use  in  high  schools  or  college  preparatory  schools. 

CLARKE'S  ELEMENTS  OF  CHEMISTRY  .         .        .     $1.20 
A  scientific  book  for  high  schools  and  colleges  intended  to 
provide  a  complete  course  for  schools  and  to  serve  as  a  sub- 
stantial basis  for  further  study. 

COOLEY'S  NEW  TEXT-BOOK  OF  CHEMISTRY   .    90  cents 
An  elementary  course  designed  for  use  in  high  schools  and 
academies.     The  fundamental  facts  and  principles  are  treated 
in  a  simple,  concise,  and  accurate  manner. 

STEELE'S  POPULAR  CHEMISTRY  ....    $1.00 
A  popular  treatise  for  high  schools,  academies,  and  private 
students. 

BREWSTER'S  FIRST  BOOK  OF  CHEMISTRY  .  66  cents 
Designed  to  serve  as  a  guide  for  beginners  in  the  simplest 
elements  of  the  science.  The  experiments  are  of  the  most 
elementary  character,  and  only  the  simplest  apparatus  is 
employed. 

LABORATORY   METHODS 

ARMSTRONG    AND    NORTON'S    LABORATORY 

MANUAL  OF  CHEMISTRY.         .  50  cents 

COOLEY'S  LABORATORY  STUDIES  IN  CHEMISTRY 

50  cents 

KEISER'S  LABORATORY  WORK  IN  CHEMISTRY     50  cents 

IRISH'S  QUALITATIVE  ANALYSIS  FOR  SECONDARY 

SCHOOLS 50  cents 


Copies  will  be  sent,  prepaid,  on  receipt  of  the  price. 

American   Book  Company 

NEW  YORK  .  CINCINNATI  •  CHICAGO 

(S.  i6o) 


This  book  is  DUE  on  the  last 
date  stamped  below 


Ok 


ve 


UC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


A     001  080  449     o 


^JMV£liSITyr'',--,-Tr,- 


^"^nRKh 


